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CHEMISTRY – REVISION SHEET
XII : CBSE
GENERAL PRINCIPLES AND PROCESSES
OF ISOLATION OF ELEMENTS
SUBJECTIVE TYPE QUESTIONS
Each Question carries 1 Mark
1.
What is meant by the term pyrometallurgy?
2.
Name two metals which occur in nature as oxides.
3.
Which of two scraps, zinc or iron, would be preferred for the recovery of copper from the leached copper
ore and why?
4.
Copper matte is charged into a silica lined convertor in extraction of copper. What is the role of silica lining
here?
5.
What type of ores can be concentrated by magnetic separation method?
6.
What is the role of graphite in the electrometallurgy of aluminium?
7.
How is copper extracted from a low grade ore of it?
8.
Why is electrolytic reduction preferred over chemical reduction for the isolation of certain metals?
9.
What is the role of collectors in froth floatation process?
10.
Write the reaction involved in the extraction of silver after the silver ore has been leached with NaCN.
11.
Name the method used for refining of nickel metal.
12.
What is the composition of copper matte?
13.
Name the method used for refining copper metal.
14.
Name the methods used for phase refining of impure titanium and nickel metal.
15.
Name the methods used for remining of germanium metal.
16.
Which reducing agent is employed to get copper from the leached low grade copper ore?
17.
What is the role of zinc metal in the extraction of silver?
18.
Name the depressant which is used to separate ZnS and PbS ores in froth floatation process.
19.
Name the process of heating in presence of oxygen so as to convert sulphide ore to oxide ore.
20.
Name the process in which a particular mineral is dissolved selectively by using acids, bases or other
reagents.
Short answer type Questions 2 marks
21.
State the basis of refining a substance by chromatographic method.
Under what circumstances is this method specially usefull?
22.
Explain the role of
(i) Cryolite in the electrolytic reduction of alumina.
(ii) Carbon monoxide in the purification of nickel.
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23.
How is chemical reduction different from electrolytic reduction? Name a metal each which is obtained by
(i) Electrolytic reduction
(ii) Chemical reduction
24.
Describe the principle controlling each of the following processes.
(i) Preparation of cast iron from pig iron.
(ii) Preparation of pure alumina (Al2O3) from bauxite ore.
25.
Describe the principle controlling each of the following processes:
(i) Vapour phase refining of titanium metal
(ii) Froth floatation method of concentration of a sulphide ores.
26.
(a) Name the method used for removing gangue from sulphide ores.
(b) How is wrought iron different from steel?
27.
Write the principle behind the froth floatation process. What is the role of collectors in the process.
28.
(a) Which solution is used for the leaching for silver metal in the presence of air in the metallurgy of
silver?
(b) Out of CO and C, which is a better reducing agent at the lower temperature range in the blast furnace,
to extract iron from the oxide ore?
29.
Write chemical reaction taking place in the extraction of copper from sulphide ores.
30.
Why the leaching of gold by metal cyanides carried out in presence of oxygen? Give the chemical equation.
Name the metal used as reducing agent.
31.
Name one example each of (i) Acidic flux (ii) Basic flux.
32.
Give two important uses of the following metals:
(a) Na
33.
(b) Mg.
Give the chemical formula of:
(a) Chile salt petre
(b) Iron pyrite.
Short Answer type Questions 3 Marks
34.
(i) Write the names of any two principal ores of zinc.
(ii) What are its uses?
35.
(i) What are main ores of iron?
(ii) What is pig iron and cast iron?
(iii) Give the uses of cast iron.
36.
What is the chief ore of iron? Write chemical reactions taking place in the extraction of iron from its ore.
37.
Describe how the following changes are brought about?
(i) Pig iron into steel
(ii) Zinc oxide metallic zinc
(iii) Impure titanium into pure titanium.
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38.
Write down the reactions which occur in upper, middle and lower zones in the blast furnace during the
extraction of iron from iron ore.
39.
Write briefly the steps to extract lead from Galena. Write the chemical reactions involved.
40.
Explain the principal of zone refining with the help of a suitable diagram. Which class of materials are
purified by this method?
41.
Why is the reduction of a metal oxide easier if the metal formed is in liquid state at the temperature of
reduction?
42.
Explain column chromatography with the help of a suitable diagram.
43.
Explain the role of each of the following in the extraction of metals from their ores:
(i) CO in the extraction of nickel.
(ii) Zinc in the extraction of silver.
(iii) Silica in the extraction of copper.
44.
Look at the following diagram and answer the following
questions given below:
(i) What is this process of extraction of Al known as?
(ii) What is the function of Na 3AlF4?
(iii) Write the overall reaction taking place in the extraction of metal.
45.
Look at the following figure and answer the questions given below.
(i) What is the name of this furnace?
(ii) What is the function of this furnace?
(iii) Write the reactions taking place in the region 900-1500 K.
Long answer type Questions 5 Marks
46.
(a) What metals are generally extracted by the electrolytic process? What positions do these metals
generally occupy in the periodic table?
(b) Write chemical reactions taking place in the extraction of coper from sulphide ores.
47.
(a) Explain smelting with the help of example.
(b) What method would you suggest for the separation of metal in the following mixtures?
(i) Zinc and iron.
(ii) Copper and magnesium
(iii) Rare earth metals.
48.
Give reasons for your choice.
(a) What is the thermodynamic consideration in the
choice of a reducing agent in metallurgy?
(b) Using the Ellingham diagram given below, predict the
following:
(i) At what temperature can silicon reduce MgO?
(ii) At what temperature can aluminium reduce MgO?
(iii) At what temperature can carbon reduce MgO?
Page 3
49.
(a) Name the metals whose salts give flame of the following colours:
(i)
Golden yellow
(ii)
Bluish green
(b) Describe the purification of bauxite ore.
50.
(a) Give two important uses of the following metals:
(i)
Na
(ii) Mg
(b) Give an account of the extraction of silver by the cyanide process. Describe briefly how a pure
sample of silver obtained by electrorefining?
PREVIOUS YEAR BOARD QUESTIONS + HOTS
51.
How does NaCN act as a depressant in preventing ZnS from forming the froth?
52.
Which of the following metal cannot be extracted by the smelting process?
53.
Suggest one method for separation of Nickel from cobalt?
54.
Both aluminum and iron combine slowly with oxygen at room temperature. Why is this reaction a problem
for iron not for aluminium?
55.
Write the overall reaction taking place in the process used for the electrolysis of alumina by Hall-Heroult
process.
Value based questions
56.
When Ram came from school, he saw his mother talking to a person who claimed that he would polish her
tarnished silver/gold bangles charging only a nominal amount of money. Out of curiosity, Ram asked the
person concerned as to how would he polish the bangles. The man showed him a silvery heavy liquid
contained in a bottle and told him that he would rub the bangles with this silvery liquid. Using his knowledge
of chemistry, Ram immediately saw through the trick and asked his mother not to get the bangles polished
and requested the man to please go away. Read this passage and answer the following questions:
(a) Name the silvery liquid with which the bangles were to be rubbed.
(b) Why did ram ask his mother not to get the bangles polished?
(c) What benefit does the man derive from rubbing the silver / gold bangles with silvery liquid?
(d) As a student of chemistry, what initiative would you take to save the innocent women in the streets and
mohallas from being cheated by quacks?
57.
Nisha visited her sister karuna‟s house and found that all the water taps were rusted. She told her that
instead of iron taps she should use nickel or chrome plated taps. She accepted her suggestion. After reading
the above passage, answer the following questions:
(a) What is the value associated with Nisha‟s suggestion?
(b) How is nickel or chrome plating carried out?
(c) Name a few nickel/chrome plated articles which are used in our daily life.
58.
Jai wanted to renovate his office. He wanted to install doors/windows made-up of iron but his friend
suggested him to use windows/doors made-up of aluminum. Jai accepted the suggestion of his friend.
After reading the above passage, answer the following questions:
Page 4
(a) What values are suggested by Jai‟s friend which changed his mind to use windows / doors made-up of
aluminum instead of iron?
(b) Give one principal ore each of iron and aluminium.
(c) How is iron aluminium abtained from their respective ores?
59.
Many metals occur in the earth‟s crust as sulphides. To extract metals, the sulphide ores are first roasted in
reverberatory furnace in excess of air when metal oxide is formed and sulphur dioxide is released. Chemical
engineer suggested the management not to release SO 2 into the atmosphere. He suggested that it should be
collected and converted into useful products like Na 2SO3, H2SO4 etc.
(a) Name three important sulphide ores.
(b) Name the method used in the concentration of sulphide ores.
(c) How SO2 is harmful for us?
(d) Mention the values shown by chemical engineer.
NCERT Intext questions with solutions
60.
Which of the ores mentioned in Table 6.1 can be concentrated by magnetic separation method?
61.
What is the significance of leaching in the extraction of aluminium?
62.
The reaction, Cr2O3  2Al  Al2O3  2Cr Go  421kJ is the modynamically feasible as is apparent


from the Gibb‟s energy value. Why does it not take place at room temperature?
63.
Is it true that under certain conditions, Mg can reduce SiO 2 and Si can reduce MgO? What are the conditions?
64.
Copper can be extracted by hydrometallurgy but not zinc. Explain.
65.
What is the role of depressant in froth floatation process?
66.
Why is the extraction of copper from pyrite difficult than that from its ore through reduction?
67.
Explain Zone refining, column chromatography.
68.
Out of C and CO, what is a better reducing agent at 673 K?
69.
Name the common elements present in the anode mud in electrolytic refining of copper.
Why are they so present?
70.
Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.
71.
Write chemical reactions taking place in the extraction of zinc from zinc blende.
72.
State the role of silica in the metallurgy of copper.
73.
What is meant by the term chromatography?
74.
What criterion is followed for the selection of the stationary phase in chromatography?
75.
Describe a method for refining nickel.
76.
How can you separate alumina from silica in a bauxite ore associated with silica? Give equations, if any.
77.
Giving examples, differentiate between „roasting‟ and „calcination‟.
78.
How is „cast iron‟ different from „pig iron‟?
79.
Differentiate between „Minerals‟ and „Ores‟.
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80.
Why copper matte is put in silica lined converter?
81.
What is the role of cryolite in the metallurgy of aluminium?
82.
How is leaching carried out in case of low grade copper ores?
83.
Why is zinc not extracted from zinc oxide through reduction using CO?
84.
The value of f Go for formation of Cr2O3 is  540 kJ mol-1 and that of Al2O3 is -827 kJ mol-1 is the
reduction of Cr2O3 possible with Al?
85.
Out of C and CO, which is a better reducing agent for ZnO?
86.
The choice of a reducing agent in a particular case depends on thermodynamic factor. How far do you agree
with this statement? Support your opinion with two examples.
87.
(i) Name the process from which chlorine is obtained as a by-product.
(ii) What will happen if an aqueous solution of NaCl is subjected to electrolysis?
88.
What is the role of graphite rod in the electrometallurgy of aluminum?
89.
Outline the principles of refining of metals by the following methods:
(i) Zone refining
90.
(ii)
Electrolytic refining
(iii)
Vapour phase refining
Predict conditions under which Al might be expected to reduce MgO.
Very short answer type questions 1 Marks
91.
Name three metals which occur in native state in nature.
92.
What are collectors in froth flotation process? Give one example.
93.
Give the names and formulae of three ores which are concentrated by froth floatation process.
94.
Among Fe, Cu, Al and Pb, which metal (s) cannot be obtained by smelting.
95.
What is the thermodynamic criteria for the feasibility of a reaction?
96.
Who CO is a better agent than C at 673 K?
97.
Indicate the temperature at which carbon can be used as a reducing agent for FeO.
98.
Why aluminium cannot be reduced by carbon?
99.
Name the most important form of iron. Mention its one use.
100. Name the impurities present in bauxite ore.
101. What is the composition of copper matte?
102. Which from of copper is called blister copper?
103. What are froth stabilizers? Give two examples.
104. A sample of galena is contaminated with zinc blend. Name one chemical which can be used to concentrate
galena selectively by froth floatation method.
105. What does a steep increase in the slope of a line on Ellingham diagram indicates.
106. What are the constituents of German silver?
107. Why is froth floatation process selected for concentration of the sulphide ore?
108. Which form of iron is used in making anchors, chains and agricultural implements?
Page 6
109. Write the reaction involved in the extraction of copper from low grade ores.
110. Although aluminium is above hydrogen in the electrochemical series, it is stable in air and water. Why?
111. Zinc is used but not copper for the recovery of metallic silver from the complex [Ag(CN 2)] although
-
electrode potentials of both zinc and copper are less than that of Ag. Explain why?
Short answer type Questions 2 marks
112. What is hydrometallurgy? Give one example where it is used metal extraction.
113. Name the process for the benefaction/concentration of (i) an ore having impurities lighter than it
(ii) Sulphide ores.
114. What is cryolite? Mention its use in the extraction of aluminium.
115. What is the role of following:
(a) SiO2 in the metallurgy of Cu.
(b) CaCO3 in the metallurgy of Fe.
116. Extraction of copper directly form sulphide ore is less favourable than from its oxide through reduction
Explain.
117. The graphite electrodes in the extraction of „Al‟ by Hall-Heroult process need to be changed frequently. Why?
118. Write the chemical formulae of the following ores (a) Haematite (b) Magnetite (c) Limonite (d) Siderite.
119. Give equations for the industrial extraction of zinc from calamine.
120. Name the elements contained in anode mud during refining of copper. Why does it contain such elements?
121. What kind of elements are suitable for purification by chromatography?
122. Write the chemical reactions taking place in different zones in the blast furnace for the extraction of iron
from its ore.
123. How are impurities separated from bauxite ore to get pure alumina?
124. Why is the reduction of a metal oxide easier if metal formed is in liquid state at the temperature of radiation?
125. Name the alloying element added to iron for making
(i)
Steel used in cutting tools and crushers.
(ii) Steel used in making cables, measuring tapes and aeroplane parts.
126. What is pyrometallurgy? Explain with one example.
127. Write the method to produce copper matte from copper pyrites.
128. Copper can be extracted by hydrometallurgy but not zinc. Explain why?
129. Free energies of formation
Gf of MgOs and COg at 1273K and 2273 K are given below:
Gf MgO s   941KJ mol1 at 1273 K.
Gf CO  g   439 KJ mol1 at 1273 K.
Gf MgO s   314 KJ mol1 at 2273 K.
Gf CO  g   628 KJ mol1 at 2273 K.
On the basis of above data, predict the temperature at which carbon can be used as a reducing agent for
MgO(s).
Page 7
Short Answer type Questions 3 Marks
130. State the principles of refining of metal by the following methods.
(a) Zone refining
(b) Electrolytic refining
(c) Vapour phase refining.
131. How is pure copper obtained from its principles ore? Write the
chemical reactions occurring during the extraction.
132. Name the method of refining of the following metals-
(a) Hg
(b) Sn
(c) Cu
(d) Ge
(e) Ni
(f) Zr
133. Suggest a condition under which:
(i) Mg can reduce alumina (Al2O3)
(ii) Al can reduce MgO.
134. The native forms a water soluble compound (B) with dilute aqueous solutions of NaCN in the presence of a
gas (A). The silver metal is obtained by the addition of a metal (C) to (B) and complex (D) is formed as d
byproduct. Write the structures of (C) and (D) identify (A) and (B) in the following sequence-
Ag  NaCN  A  H2O  B  OH  Na  .
C  B  D  Ag.
Page 8
COORDINATION COMPOUNDS
Very short answer type questions 1 Marks
1.
Write IUPAC name of the complex : Cr  H2O5 Cl Cl2 .
2.
Write IUPAC name of the complex : Co  NH3 5 SCN Cl2
3.
Write the formula of copper hexacyano-ferrate (II).
4.
Describe briefly the following : Isomerism shown by Cr  H2O5  NCS
5.
Write an ionisation isomer of Cr  H2O5 Br  SO4 .
6.
Write the IUPAC name of Co  en 2  NH3 2  Cl3.
7.
2
Write the IUPAC name of Co  NH3 5 Cl Cl2 .
3
8.
What is the coordination number of central metal ion in Fe  C2O4 3  .
9.
Write IUPAC name for Pt  NH3 2 Cl4 
10.
Write IUPAC name for Ag  NH3 2  NO3.
11.
What scheme of hybridisation is proposed for Co in Co  NH3 6  ?
12.
Write formula for pentaamminecholor-platinum (IV) chloride.
13.
Write IUPAC name of the complex Na3 Cr  OH2 F4  .
14.
Write the IUPAC name of the  NH4 2 Co  ONO6  .
15.
Write an anion whose shape can be explained by the scheme of sp3d2 hybridisation.
2
3
Short answer type Questions 2 marks
16.
Using the valence bond approach, deduce the shape and magnetic character of Cr  CO6  .
[Atomic number of Cr = 24]
3
17.
Using the valence bond approach, predict the shape and magnetic character of Fe  CN 6  ion.
18.
Using the valence bond approach, deduce the shape and magnetic character of Co  NH3 6  .
3
[Atomic number of Co = 27]
19.
Using the valence bond approach, predict the shape and magnetic behaviour of CoCl4  .
2
[Given, atomic number of Co = 27]
20.
Write the IUPAC name of the following :
(i) Mn  H2O6 
2
(ii) Cr  NH3 6 
3
Page 9
21.
Write the state of hybridisation and oxidation state of central atom in each of the following species:
(i) cis Co  NH3 4 Cl2 
22.

(ii) PtCl3  C2H4 

Giving suitable example describe the importance of the formation of complex compound in the extraction
of a particular metal from its natural source.
23.
How is the magnitude of 0 affected by (i) nature of ligands and (ii) oxidation state of metal ion?
24.
Draw the structures and write the hybridized state of the central atom of each of the species.
(ii) trans – [Co(NH3)4Cl2]+.
(i) Fe(CO)5
3
25.
Using the valence bond approach, deduce the shape and magnetic behaviour of Cr  NH3 6  ion.
26.
Illustrate with an example ionnisation isomerism in coordination compounds.
27.
Deduce the shape and magnetic behaviour of the complex ion Co  NH3 5 NO2  .
2
[Atomic number of Co = 27]
28.
Using the valence bond theory, predict the shape and magnetic behaviour of [Cr(NH 3)5Cl]2+ ion.
[Atomic number of Cr = 24]
29.
Among Ag  NH3 2  Cl,  Ni  CN4 
(i)
2
and CuCl4  which :
2
has square planar geometry?
(ii) Remains colourless in aqueous solutions and why?
[Atomic number of Ag = 47, Ni=28,Cu=29]
30.
Explain the following
(i)
Co  NH3 6  is diamagnetic whereas CoF6  is paramagnetic.
3
3
3
3
(ii) Fe  H2O6  is more paramagnetic than Fe  CN 6  .
Short Answer type Questions 3 Marks
31.
(a) What is a ligand? Give an example of bidentate ligand.
2
(b) Explain as to how the two complexes of Ni,  Ni  CN4  and Ni(CO)4 have different structures but
do not differ in their magnetic behaviour (Ni = 28).
32.
(a) What is the basis of formation of spectrochemical series?
(b) Draw the structures of geometrical isomers of the coordination complexes:

Co  NH3 3 Cl3  and CoCl2  en 2  .
33.
Write the name and draw the structure of each of the following complex compounds:
(i) Co  NH3 4 (H2O)2  Cl3
(ii) Pt  NH3 4   NiCl4 
(iii)
Co en2 Cl2 ]Cl
Page 10
34.
Describe for any two of the following complex ions, the type of hybridisation, shape and magnetic
property:
(i)
Fe  H2O6 
2
Co  NH3 6 
(ii)
3
(iii)
 NiCl4 2
[Atomic number of Fe = 26, Co = 27, Ni = 28]
35.
Explain :
(a) Linkage isomerism
(b) Coordination isomerism
(c) Why is  NiCl4 
2
36.
paramagnetic?
 Ni  28
Write the IUPAC name of [Co(en)2Cl2]Cl and draw the structures of all the isomers with this formula of
complex.

37.
Write the name (IUPAC norm) and draw the possible optical isomers of CrCl2  en  NH3 2  .
38.
(a) What are ambidentate ligand? Give an example.
(b) Write IUPAC name of the following:
(i) K3 Fe  C2O4 3 


(ii) Pt(NH3 )6 Cl4.

(c) Draw the structure of cis-isomer of Co  NH3 4 Cl2  .
39.
Draw the structures of following:
(a) Cis-dichlorotetracyanochromate (III)
(b) Pentaamminenitrito-N-cobalt (III)
(c) Hexamethyldialuminium
40.
Draw a sketch to show the splitting of d-orbitals in an octahedral and crystal field. State for a d6 ion how the
actual configuration of the split d-orbitals in an octahedral crystal field is decided by the relative values of
0 and P.
Long answer type Questions 5 Marks
41.
(a) Amongst the following, the most stable complex is:
(i) Fe  H2O6 
42.
3
(ii) Fe  NH3 6 
3
(ii) Fe  C2O4 3 
3
(iv)  FeCl6 
3
2
(a) Using valence bond approach, explain the shape and magnetic behaviour of  Ni  NH3 6  .
(b) A coordination compound has the formula CoCl4. 4NH3. It does not liberate ammonia but forms a
precipitate with AgNO3. Write the structure and IUPAC name of the complex compound.
43.
(a) Describe briefly the nature of bonding in metal carbonyl.
(b) Answer the following:
(i) Name two main factors that favour a metal ion‟s forming complex.
(ii) Give an example of industrial application of formation of coordination complex.

(iii) Write the IUPAC name of Co  en 2 Cl  ONO .
Page 11
44.
45.
2
(a)
Illustrate the geometrical isomerism with the help of an example Pt  NH3 4 Cl2  .
(b)
Answer the following:
(i)
Differentiate between a bidentate ligand and a monodentate ligand.
(ii)
Write the IUPAC name of Pt  NH3 2 Cl2  Cl2 .
(iii)
Draw the structures of geometrical isomers of Co  NH3 4 Cl2  .
(a)
Mention applications of coordination compounds in following areas giving an example of each:

(i) Analytical chemistry.
(b)
(ii) Extraction of metals.
Formation of complex is exothermic or endothermic process. Explain why.
What is the effect of temperature on stability of complex compounds?
PREVIOUS YEAR BOARD QUESTIONS + HOTS
46.
Calculate :

(i) Ratio of Ag  NH3 2  and Ag  in 0.1M NH3 solution.
3
(ii) Ratio of Ag S2O3 2  and Ag  in 0.1M S2O32 solution.
Given that the stability / formation constant
 Kf  for Ag  NH3 2 
47.

3
and Ag S2O3 2  are1.7 107 and1.0 1013 respectively.
Dimethyl glyoxime is added to alcoholic solution of NiCl2. When ammonium hydroxide is slowly added to
it, a rosy red precipitate of complex appears.
(i)
Give the structure of the complex showing hydrogen bonds.
(ii)
Give oxidation state and hybridisation of central metal ion.
(iii)
Identify whether it is paramagnetic or diamagnetic.
Value based questions
48.
In villages, people often wash their clothes with well water. They have to rub a lot of soap before lather is
formed. This is because well water is hard water. Thus, a lot of soap is wasted. However, if the they use
detergent powder in place of soap, lather is formed easily and wastage is less.
Now, answer the following questions:
49.
(i)
What values are expressed in the above paragraph?
(ii)
Why soap does not form lather with hard water?
During war, arsenic containing poisonous gas called Lewisite is sometimes used. The soldiers may get
affected due to poisoning by arsenic or it may affect the people living in the nearby areas. Similarly, we use
a number of articles containing lead. If some how it lead pipes are used for transport of water, there may be
lead poisoning. The person inflicted with arsenic or lead poisoning has to be given an antidote. Now,
answer the following questions:
(i)
What values are expressed in the above paragraph?
(ii)
Which antidote is given for arsenic poisoning and which one for lead poisoning?
Page 12
50.
Cancer symptoms are changes in the body caused by the presence of cancer. They are usually caused by the
effect of a cancer on the part of the body where it is growing, although the disease can cause more general
symptoms such as weightloss or tiredness. Coordination compounds have an important role in the field of
medicines. Out of these, the compounds cis-platin is quite effective against cancer.
(i)
(ii)
(iii)
51.
What is the chemical formula and IUPAC name of the coordination compound?
How does it behave as anti-cancer agent?
What is the value associated with the use of cis-platin?
Rajesh a student of class XII chemistry wanted silver plating on a decoration piece, so he visited an
electroplating shop. The shop owner showed him plated samples but Rajesh observed them to be dull and
unsmooth. When he pointed out the poor electroplating, the concerned person told him that a good quality
of silver nitrate solution was used for the Purpose. Rajesh being a student of chemistry suggested the use of
a solution of sodium argentocyanide instead of silver nitrate solution. This change worked and silver plating
was bright and uniform.
(i)
(ii)
(iii)
Name three important sulphide ores.
Name the method used in the concentration of sulphide ores.
What is the value attached with the student‟s approach?
NCERT Intext questions with solutions
52.
53.
Write the formulas for the following coordination compounds:
(i)
Tetraamminediaquacobalt (III) chloride
(ii)
Potassiumtetracy anonickelate (II)
(iii)
Tris (ethane-1,2-diammine) chromium (III) chloride
(iv)
Amminebromidochloridontitrito-N-platinate(II)
(v)
Dichloridobis (ethane-1,2- diammine) platinum (IV) nitrate
(vi)
Iron (III) hexacyanoferrate(II).
Write the IUPAC names of the following coordination compounds:
(ii)
Co  NH3 6  Cl3
Co  NH3 5 Cl Cl2
(iii)
K3 Fe  CN 6 
(iv)
K3 Fe  C2O4 3 
(i)
54.
(v)
K2 PdCl4 
(vi)
Pt  NH3 2 Cl  NH2CH3  Cl
Indicate the types of isomerism exhibited by the following complexes and draw the structures for these
isomers:
(i)
K Cr  H2O2   C2O4 2

(iii)
Co  en 3  Cl3
Co  NH3 5  NO2   NO3 2
(iv)
Pt  NH3  H2O Cl2 
(ii)
Page 13
55.
Give evidence that Co  NH3 5 Cl SO4and Co  NH3 5 SO4  Cl are ionisation isomers.
56.
Explain on the basis of valence bond theory, that  Ni  CN4  ion with square planar structure is
2
diamagnetic and the  NiCl4  ion with tetrahedral geometry is paramagnetic.
2
57.
 NiCl4 2 is paramagnetic
58.
Fe  H2O6 
59.
Explain Co  NH3 6  is an inner orbital complex whereas  Ni  NH3 6 
60.
Predict the number of unpaired electrons in the square – planar Pt  CN4  ion.
61.
The hexaquamanaganese (II) ion contains five unpaired electrons while the hexacyanoion contains only one
3
while  Ni  CO4  is diamagnetic though both are tetrahedral. Why?
is strongly paramagnetic whereas Fe  CN 6 
3
3
is weakly paramagnetic. Explain.
2
is an outer orbital complex.
2
unpaired electron. Explain using Crystal Field theory.
62.
2
Calculate the overall complex dissociation equilibrium constant for the Cu  NH3 4  ion, give that 4 for
this complex is 2.11013.
63.
Explain the bonding in coordination compounds in term of werner‟s postulates.
64.
FeSO4 solution mixed with
 NH4 2 SO4 solution in 1 : 1 molar
ratio gives the test of Fe 2+ ion but CuSO4
solution mixed with aqueous ammonia in 1 : 4 molar ratio does not give the test of Cu 2+ ion. Explain why?
65.
Explain with two examples each of the following:
Coordination entity, ligand, coordination number, coordination polyhedron, homoleptic and heteroleptic.
66.
What is the meant by unidentate, didentate and ambidentate ligands? Give examples for each.
67.
Specify the oxidation numbers of the metals in the following coordination entities:
(i)
(ii)
(iii)
(iv)
(v)
68.
Co  CN H2O en 2 
2
PtCl4 2
CrCl3  NH3 3 

CoBr2  en 2 
K3 Fe  CN6  .
Using IUPAC norms write the formulae for the following:
(i)
Tetrahydroxozincate (II)
(ii)
Potassiumtetrachloridopalladate (II)
(iii)
Diamminedichloridoplatinum (II)
(iv)
Potassiumtetracyanonickelate (II)
(v)
Pentaamminenitrito-O-cobalt (III)
(vi)
Hexaamminecobalt (III) sulphate
Page 14
(vii) Potassiumtri (oxalate) chromate (III)
(viii) Hexaammineplatinum (IV)
69.
(ix)
Tetrabomocuprate(II)
(x)
Pentaamminenitrito-N-cobalt (III).
Using IUPAC norms write the systematic names of the following:
(ii)
Co  NH3 6  Cl3
Pt  NH3 2 Cl  NH2CH3  Cl
(iii)
Ti  H2O6 
(iv)
Co  NH3 4 Cl  NO2  Cl
(v)
Mn  H2O6 
(i)
(vi)
(vii)
3
 NiCl4 2
 Ni  NH3 6  Cl2
(viii) Co  en 3 
(ix)
3
3
 Ni  CO4  .
70.
List various types of isomerism possible for coordination compounds, giving an example of each.
71.
How many geometrical isomers are possible in the following coordination entities?
(i) Cr  C2O4 3 
72.
3
(ii) PtCl2  en 2 
2
(iii) Cr  NH3 2 Cl2  en 

Draw all the isomers (geometrical and optical) of:
(i) CoCl2  en 2 
74.
(ii) Co  Cl3 (NH3 3 
Draw the structures of optical isomers of:
(i) Cr  C2O4 3 
73.
3

(ii) Co  NH3  Cl  en 2 
2
(iii) Co  NH3 2 Cl2  en 

 
Write all the geometrical isomers of Pt  NH3  Br  Cl  Py  and how many of these will exhibit optical
isomerism?
75.
Aqueous copper sulphate solution (blue in colour) gives (i) a green precipitate with aqueous potassium
fluoride and (ii) a bright green solution with aqueous potassium chloride. Explain these experimental results.
76.
What is coordination entity formed when excess of aqueous KCN is added to an aqueous solution of copper
sulphate? Why is that no precipitate of copper sulphate is obtained when H 2S (g) is passed through this
solution.
77.
Discuss the nature of bonding in the following coordination entities on the basis of valence bond theory:
(i) Fe  CN 6 
78.
4
(ii)  FeF6 
3
(iii) Co  C2O4 3 
3
(iv) CoF6 
3
Draw figure to show the splitting of d orbitals in an octahedral crystal field.
Page 15
79.
What is spectrochemical series? Explain the difference between a weak field ligand and a strong field ligand.
80.
What is crystal field splitting energy? How does the magnitude of 0 decide the actual configuration of dorbitals in a coordination entity?
2
81.
Cr  NH3 6  is paramagnetic while  Ni  CN4 
82.
A solution of  Ni  H2O6  is green but a solution of  Ni  CN4 
83.
Fe  CN 6 
84.
Discuss the nature of bonding in metal carbonyl.
85.
Give the oxidation state d-orbital occupation and coordination number of central metal ion in the following
3
is diamagnetic. Explain why?
2
4
and Fe  H2O6 
2
2
is colourless. Explain.
are of different colours in dilute solutions. Why?
complexes:
(i) K3  Co(C2O4 3 
86.

(ii)  NH4 2 CoF4

(iii) cis  Cr  en 2 Cl2  Cl
(iv) Mn  H2O6  SO4
Write down the IUPAC name for each of the following complexes and indicate the oxidation state, electronic
configuration and coordination number. Also, give stereochemistry and magnetic moment of the complex.
87.
What is meant by stability of a coordination compound in solution? State the factors which govern stability
of a complexes.
88.
What is menat by chelate effect? Give an example.
89.
Discuss briefly giving an example in each case the role of coordination compounds:
90.
(i) biological system
(ii) analytical chemistry
(iii) medical chemistry
(iv) extraction / metallurgy of metals.
How many ions are produced from the complex, Co(NH 3)6Cl2 in solution?
(i) 6
91.
(ii) 4
(iii) 3
(iv) 2
Amongst the following ion, which one has the highest magnetic moment?
(i) Cr  H2O6 
3
(ii) Fe  H2O6 
2
(iii)  Zn  H2O6 
92.
The oxidation number of cobalt in K Co  CO4  is.
93.
Amongst the following, the most stable complex is:
3
(i) Fe  H2O6 ]
94.
3
(ii) Fe  NH3 6 ]
2
(iii) Fe  C2O4 3 
3
(iv)  FeCl6 
3
What will be the correct order for the wavelengths of absorption in the visible region of the following:
4
2
 Ni  NO2 6  ,  Ni  NH3 6  ,  Ni  H2O6 
2
Each Question carries 1 Mark
95.
Define coordination compounds?
96.
Write the names of counter ions in
(i) Hg Co SCN4  and
(ii) Pt  NH3 4  Cl2.
Page 16
97.
Calculate the oxidation state of nickel in  Ni  CO4  .
98.
Calculate the coordination number of central atom in Co  C2O4 3  .
99.
What is the coordination number of iron in Fe  EDTA ?
3

100. Which complex compound is used in chemotherapy? Write its formula also.
101. Name the compound used to estimate the hardness of water volumetrically.
102. Give the IUPAC name of
Pt Cl2  NH2CH3 
 NH3 2  Cl.
103. How many geometrical isomers are possible for the complex [Ni(CO) 4], which is tetrahedral in nature?
104. Arrange the following in the increasing order of conductivity in solution.
 Ni  NH3 6  Cl2 ; Co  NH3 6  Cl3 and CoCl2 en 2  Cl
105. Arrange the following ligands in increasing order of
0 (Crystal field splitting energy for octahedral
complexes): Cl , NH3 ,I ,CO,en.
106. Write I.U.P.A.C. name of Tollen‟s reagent.
107. Define the term stability of a complex in solution.
108. Calculate the overall dissociation equilibrium constant for the
2
Cu  NH3 4  ion. Given that overall
stability constant 4  for this complex is 2.11013.
109. What is a chelate ligand? Give one example.
110. Write the I.U.P.A.C name of
Li AlH4 .
111. Name one homogeneous catalyst used in hydrogenation of alkenes.
112. Whether
113.
Co  NH3 6  show any optical isomerism? Give reason for this.
Ti  H2O6  Cl3 is coloured but on heating becomes colourless. Why?
114. What is the formula of Fisher salt?
115. Write the formula and the name of the coordinate isomer of
Co  en 3  Cr  CN6  .
Each Question carries 2 Marks
116. Write two differences between a double salt and a coordination complex with the help of an example.
117. Mention the main postulates of werner‟s Theory.
118. Define (a) Homoleptic and (b) Heteroleptic complexes with the help of one example of each.
119. In the following coordination entity
Page 17
(a) Identify the ligand involved and
(b) Oxidation state of copper metal.
120. Are the bidentate ligands same as the amibidentate ligands? Justify with one example.
121. Calculate the magnetic moments of the following complexes:
(i) Fe  CN 6 
(ii) CoF6 
4
3
122. Explain the following
(a) All octahedral complexes of Ni2+ must be outer orbital complexes.
(b) NH4+ ion does not form any complex.
123. What type of structural isomerism is represented by the following pairs:
(a) Mn  CO5 SCN and Mn  CO5 NCS
(b) Co  NH3 5 NO3  SO4 and [Co  NH3 5 SO4 ]NO3
124. How complex compounds are applicable in (a) electroplating of silver, gold or other noble metals (b) in
photography.
125. Mention two limitations of crystal Field Theory.
126. Derive a relationship between stepwise stability constants and overall stability constant of a complex in the
solution. How overall stability constant varies with dissociation equilibrium constant?
127. Explain as to how complexes of nickel
differ in their magnetic behaviours.
2
 Ni  CN4  and Ni  CO4 have different structures but do not
At.no.of Ni  28 .
128. Draw the structures of geometrical isomers of coordination complexes-
Co  NH3 3 Cl3  and CoCl2 en 2 

129. Write the IUPAC name of the complexes:
(a)  NiCl2  PPh3 2 
(b)  Ni  dmg 2 
130. How does EDTA help as a cure for lead poisoning?
131. A complex is prepared by mixing CoCl3 and NH3 in the molar ratio of 1 : 4, 0.1 m solution of this complex
was found to freeze at -0.372oC. what is the formula of the complex?
Kf of water  1.86o C / m
132. Explain using Crystal Field Theory: The
2
Mn  H2O6  ion contains five unpaired electrons while
4
Mn  CN 6  ion contains only one unpaired electron.
Each Question carries 3 Marks
133. Explain the following by giving one example in each case:
(a)
(b)
Linkage isomerism
An outer orbital complex with coordination no. 6.
(c)
A bidentate ligand.
Page 18
134. Compare the following complexes with respect to their shape, magnetic behaviour and the hybrid orbitals
involved.
(a) CoF6 
(b) Cr  NH3 6 
3
3
(c) Fe  CN 6 
4
135. Draw the structure of
(a) Cis – dichloridotetracyanochromate (II) ion
(b) Mer-triaminetrichloridocobalt (III)
(c) Fac-triaquatrintrito-N-cobalt (III)
136. Name the central metal atom/ion present in (a) chlorophyll (b) Haemoglobin (c) Vitamin B – 12.
137. A metal complex having composition Cr(NH 3)4 Cl2Br has been isolated in two forms „A‟ and „B‟. The form
„A‟ reacts with AgNO 3 solutions to give white precipitate which is readily soluble in dilute aqueous
ammonia, whereas „B‟ gives a pale yellow precipitate which is soluble in concentrated ammonia solution.
Write the formula of „A‟ and „B‟. Also mention the isomerism which arises among „A‟ and „B‟.
138. Write the limitations of valence Bond Theory.
139. Draw a sketch to show the splitting of d-orbitals in an octahedral crystal field state for a d ion. How the
6
actual electronic configuration of the split d-orbitals in an octahedral crystal field is decided by the relative
values of 0 and pairing energy (P)?
140. For the complex
Fe  en 2 Cl2  Cl identify :
(a)
The oxidation no. of iron.
(b)
The hybrid orbitals and the shape of the complex.
(c)
The magnetic behaviour of the complex.
(d)
The number of geometrical isomers.
(e)
Whether there is an optical isomer also?
(f)
Name of the complex. [At. No. of Fe = 26]
141. A chloride of fourth group cation in qualitative analysis gives a green coloured complex [A] in aqueous
solution which when treated with ethane -1, 2-diamine (en) gives pale – yellow solution [B] which on
subsequent addition of ethane -1, 2- diamine turns to blue/purple [C] and finally to violet [D].
Identify the complex forming element and [A], [B], [C] and [D] complexes,
Page 19
ELECTRO CHEMISTRY
Each Question carries 1 Mark
1.
How much charge is required for the reduction of 1 mole of Cu2 to Cu?
2.
Define secondary batteries.
3.
Define fuel cell.
4.
Rusting of iron is quicker in saline water than in ordinary water.
5.
Name the type of cell which was used in Apollo space programme for providing electrical power.
Ans. Fuel cell.
6.
What is meant by limiting molar conductivity?
7.
Express the relation among the conductivity of a solution in the cell, the cell constant and the resistance of
solution in the cell.
8.
Give the relationship between equivalent and molar conductance?
9.
How is cell constant calculated from conductor values?
10.
What are units of molar conductivity?
11.
What flows in the internal circuit of galvanic cell?
12.
Aluminum metal cannot be produced by the electrolysis of aqueous solutions of aluminum salt. Why?
13.
Account for the following: Alkaline medium inhibits the rusting of iron.
14.
Define Molar conductivity
15.
An electrochemical cell stops working after sometime. Why?
16.
2
2Cr3  aq  3Fe s
Calculate Ecell for following: 2Cr s  2Fe aq 
17.
Sn2  2MnO4 
 2Mn2  Sn4 where the reaction will proceed?
18.
Tell the reducing agent from following: Ag,Cu,Fe,K,Mg,Cr
19.
Explain with an example, how weak and strong electrolytes can be distinguished?
20.
 Zn
Calculate EZn2 /Zn For following: Zn2  2e 
21.

 96500 V.
Calculate Gfor Ecell
22.
Illustrate with the help of a diagram how the molar conductivities of (i) a strong electrolyte and (ii) a weak
Ans. Cell constant  Specific conductan ce
observed conductace
-1
2
Ans. Ohm cm mol-1or S cm2 mol-1.
Ans. Ions.
 m  .
Ans. 0.261 V
Ans.-0.79 V
Ans. G  212.3 kJ mol1
electrolyte vary with dilution of solution. Give a reason for these variations.
23.
Express the relation among cell constant, resistance of the solution in the cell and conductivity of the
solution. How is molar conductivity of a solution related to its conductivity?
Ans. m 
1000
C
24.
Predict the products of electrolysis in the following. A solution of H 2SO4 with platinum electrodes.
25.
Conductivity of 0.001 M CH3COOH is 4 105 Scm1. Calculate the dissociation constant of acetic acid. If
molar conductivity at infinite dilution for acetic acid is 390 S cm2 mol-1?
Ans.  1.17 105
Page 20
26.
Explain with examples the terms weak and strong electrolytes.
27.
Iron does not rust even if zinc coating is broken in a galvanized iron pipe.
28.
Explain rusting of iron.
29.
State Faraday‟s first law of electrolysis. How much charge in terms of Faraday is required for the reduction
of 1 mole of Cu2 + to Cu.
30.
For Ag2O (s)  2H2 O  2e 
 2Ag(s)+2OH-(aq)
Ecell  0.80 V,1F  96500 C mol1 calculate Go
31.
Ans.  301080 J  301.08 kJ.


Calculate the emf of the cell Mg(s) | Mg2  0.1M || Cu 2 1103 M | Cu(s)
Given , Ecu2 /cu  0.34 V,EMg2 /Mg  2.37V)
32.
Ans. Ecell  2.651V.
Calculate the equilibrium constant for the reaction.
Fe(s)  Cd2  aq
Fe2 (aq)  Cd(s)
 0.40 V, EFe2Fe  0.44V
Given, E
Cd2 /Cd
33.
Ans. KC  2.270 101  22.7
A Voltaic cell is set-up 25oC with the following half cells.
Ag 0.001M | Ag and Cu2 0.10M | Cu what would be the voltage of this cell?
[Given, E
cell  0.46V ]
34.
Ans. Ecell = 0.3125 V
One half cell in a voltaic cell is constructed from a silver wire dipped in silver nitrate solution of unknown
concentration. The other half cell consists of a zinc electrode in a 1.0 M solution of Zn(NO 3)2. A Voltage of
1.48 V is measured for this cell. Use this information to calculate the concentration of silver nitrate


solution. Given , EZn2 /Zn  0.763V,EAg/Ag  0.80V)
35.
Ans.  4.406 102 M
A voltaic cell is set up at 25oC with the following half cells Al | Al3+(0.001M) and Ni| Ni2+(0.50 M) write an
equation for reaction that occurs when the cell generates an electric current and determine the cell potential.




Given ENi2 /Ni  0.25V,and EAl3 /Al  1.66V log 8 106  5.0969)]
36.
Ans. ECell  1.4602 V
A copper silver cell is set-up. The copper ion consecration is 0.10 M. The concentration of silver ion is not
known. The cell potential when measured was 0.422 V. Determine the concentration of silver ions in the

 0.34V]
cell. [Given, EAg /Ag  0.80V,ECu
2
/Cu
37.
Determine the values of equilibrium constant (K c) and G for the following reaction.
Ni(s)  2Ag (aq) 
Ni2 aq  2Ag(s).
38.
Ans. 7.17 102 M.
E  1.05V 1F  96500 C mol1 
Ans. KC  3.284 1035
2
2
For the cell: Zn(s) | Zn  2M || Cu (0.5) | Cu(s)
(i)
Write equation for each half reaction.
(ii)
Calculate the cell potential at 25o C.


[Given , EZn2 /zn  0.76V; ECu2 /cu  0.34V]
Page 21
39.
Calculate the potential for half cell containing 0.10 M K 2 Cr2O7 (aq), 0.20 M Cr3+ (aq) and
2Cr3 (aq)  7H2O(I) and
1.0104 MH (aq). The half cell reaction is Cr2O72 aq 14H  6e 
the standard electrode potential is given as E  1.33 V.
40.
Ans. 0.7833 V
Calculate the equilibrium constant , K for the reaction at 298 K,
Zn s  Cu2 aq
Zn2 aq   Cu s ; G  212.300 kj mol1

[Given, E
 0.76 V;ECU
 0.34 V]
2
Zn2 /zn
/Cu
41.
Ans. KC  1.6 1037
In the button cell, widely used in watches. The following reaction takes place
Zn s  Ag2O(s)  H2OI 
Zn2 aq  2Ag s  2OH aq
Given,E   0.80V;E 2  0.76V
Ag /Ag
Zn /zn


42.
Ans.  301080 J  301.08kJ.
2Fe2 aq  I2 (s) has
The cell in which the following reaction occurs 2Fe3 aq  2I aq 
Ecell  0.236Vat 298 K. Calculate the standard Gibbs energy and the equilibrium constant of all the
reaction. (Antilog 6.5  3.162 106 , Antilog 8.0  10 108 , Antilog 8.5  3.162 108 )
Ans.  45.548kJmol1.
43.
(a)
What is electrochemical equivalent?
(b)
Calculate the cell emf and r G for the cell reaction at 25o C.

| Zn s Zn2 0.1M || Cd2 0.01M | Cd s [Given EZn2 /zn  0.763 V, ECd
 0.403V,
2
/Cd
Ans.  0.36V
44.
A strip of nickel metal is placed in a 1-molar solution of Ni(NO3)2 and a strip of silver metal is placed in a
1-molar solution of AgNO3. An electrochemical cell is created when the two solutions are connected by a
salt bridge and the two strips are connected by wires to a voltameter.
(a)
Write the balanced equations for the overall reaction occurring in the cell and calculate the cell
potential.
(b)
Calculate the cell potential E, at 25oC for the cell if the initial concentration of Ni(NO 3)2 is 1.00 molar
and the initial concentration of AgNO 3 is 1.00 molar.
E

Ni2 /Ni
45.

 0.25 C;EAg /Ag  0.80V;log101  1
Ans. 1.0795 V.
(a)
What is primary cell? Give an example.
(b)
Conductivity of 0.00241 M acetic acid solution is 7.896 105 Scm1 . Calculate its molar conductivity
in this solution if. m for acetic acid be 390.5 S cm2 mol-1. What would be its dissociation constant?
Ans. Ka  1.69 10 5
Page 22
46.
(a)
What is nickel cadmium cell? State is one merit over lead storage cell. Write the overall reaction that
occurs during discharging of this cell.
(b)
Silver is electrodeposited on a metallic vessel of total surface area 900 cm2 by passing a currnet of 0.5
ampere for 2 hours. Calculate the thickness of silver deposited, given its density is 10.5 g cm-3. (At
Ans.  4.27 104 cm
mass of Ag = 108 a.m.u).
47.
The following electrochemical cell has been set-up Pt 1| Fe 3,Fe 2 a 1 | Ce 4,Ce

Fe3 /Fe2
E
48.
 0.77 V, E

Ce4 /Ce3
3
a 1 |Pt 2

 1.61V if an ammeter is connected between the two platinum electrodesm
predict the direction of flow of current, the current increase or decrease with time?
Tarnished silver contains Ag2S. can this tarnish be removed by placing tarnished silver ware in an
aluminum pan containing an inert electrolytic solution such as NaCI? The standard electrode potential for
the half reactions are:
Ag2Ss  2e 
Ag(s)  S2 is  0.71V
Al3  3e 
2Al s
 0.95 V
is 1.66 V
Ans.
49.
What is a galvanic cell?
50.
Give the cell representation for Daniell cell.
51.
Mention the purpose of salt – bridge placed between two half cells of a galvanic cell?
52.
Give the condition for Daniell cell in which there is no flow of electrons or current or we can conclude that
there is no chemical reaction.
53.
How is electrode potential from cell potential?
54.
Can you store zinc sulphate solution in a copper container? Give suitable reason.
55.
How does electrochemical series help us in predicting whether a redox reactions is feasible in a given
direction or not?
56.
n
M(s) at 298 K and 1 atm pressure.
Write Nernst equation for the electrode reaction . M (aq)  ne 
57.
As per electrochemical series and on the basis of E o values, identify the following.
(a) Gas which has highest tendency for reduction.
(b) Weakest oxidising ion.
58.
List the two factors that influence the value of cell potential of a galvanic cell.
59.
How is equilibrium constant of a reaction related to standard cell potential?
60.
Why is equilibrium constant K related to only Eocell and not Ecell?
61.
Define cell constant. Mention the SI unit of cell constant.
62.
How does specific conductance vary with temperature?
63.
What is the SI unit of (i) conductance; (ii) conductivity.
64.
Explain concentration cell with a suitable example.
65.
State one difference between a primary battery and secondary battery.
Galvanized iron does not corrode even if the coating of zinc is broken. Explain why?
66.
Given E F2/ Fe  0.44V; EZn2 /zn  0.76V]
Page 23
67.
Define the term „Faraday constant‟. What is its numerical value?
68.
Write the name of a chemical substance which is used to prevent corrosion.
69.
Write is the direction of flow of electrons in the following cell? Zn s | Zn2 aq || Ag aq | Ag
70.
Rusting of iron becomes quicker in saline water. Explain.
71.
Two metals A and B have reduction potential values of -0.25 V and 0.80 V respectively. Which of these
Ans. Bisphenol
will liberate hydrogen gas from dilute H 2SO4?
72.
Express the relation between conductivity and molar conductivity.
73.
Name the cell which was used in Apollo space programme.
74.
How many Faraday‟s are required to oxidize 1 mole of H 2O2 to O2. .
75.
List four differences between metallic conductance and electrolytic conductance.
76.
List two differences between electrochemical cell and electrolytic cell.
77.
List four factors which affect the conductivity of ionic solutions.
78.
A conventional method of representing a Daniel cell is Zn s Zn2 1M || Cu2 1M | Cu S .
Ans. 2F
(i)
Draw a diagram of the cell and mark anode and cathode as current is drawn from the cell.
(ii)
Write the reactions taking place at the cathode and the anode during the operation of dainel cell.
79.
Suggest a method of determine the m value of water.
80.
Write the cell reaction which occur in the lead storage battery (a) when the battery is in use (b) when the
battery is on charging.
81.
Why absolute value of electrode potential cannot be determined?
82.
Account for the fact that when chlorine is passed through a fluoride solution, no reaction takes place
o
(Given EoF2/2F  2.87V;ECl
83.
2 /2Cl

 1.36V) .
Copper does not dissolve in HCl (aq) but dissolves in HNO 3 (aq) producing Cu2+ ions.
Explain the difference in behavior.
o
[Given EoCu2 /Cu  0.34V;ECl
84.
85.

2 /2Cl
 1.36V and NO3  4H  3e 
 No(g)  2H2O EoNO1 /NO  0.97V]
3
Explain the following observations:
(a)
The product of electrolysis of molten NaCl are sodium metal and chlorine gas.
(b)
The product of electrolysis of aqueous sodium chloride solution are NaOH, Cl2 and H2
What are fuel cells? Describe the principle and overall reaction involved in the working of hydrogen
oxygen fuel cell.
86.
Explain the meaning of the terms
(a) Ionic Mobility.
87.
(b) Over Voltage.
What is electrochemical series? List its two characteristics.
Page 24
88.
89.
Some standard reduction potential are as given below:
Half cell
Eo Value
F2/F-
2.9V
+
Ag /Ag
0.8V
+
Cu /Cu
0.5V
Fe2+/Fe
-0.4V
Na+/Na
-2.7V
K+/K
-2.9V
(a)
Arrange oxidising agents in order of increasing strength.
(b)
Which of these oxidising agents will oxidize Cu to Cu+ under cathode conditions?
Account for the following observations:
(a)
In a dry cell, the build up of ammonia gas around the carbon cathode should disrupt the electric
current, but in practice this does not happer.
(b)
90.
Ordinary dry cells are not rechargeable.
The following figure shows two electrolytic cells connected in series.
(a)
How much electricity is required for the reduction of 1 mole of Ag+ ions to Ag?
(b)
If three Faradays of electricity is passed through these cells what is the ratio of cation [Ag + and Cu2+]
deposited on cathodes?
Ans. (a) 1F, (b) 2 : 1]
91.
92.
(a)
Which substance act as anode and which as cathode?
(b)
Which electrolyte is used in the cell?
(c)
What is the cell potential of the cell?
Two platinum electrodes are dipped in an aqueous solution of copper sulphate which is blue in colour.
A current is passed through it.
Page 25
93.
(a)
What will happen on the two electrodes? Give equations.
(b)
What will happen to the colour of this solution?
Using the standard electrode potential, predict the reaction, if any that occurs between the following:(a)
Fe3 (aq) and I  aq  ,EoFe3 /Fe2  0.77V;Elo /2l  0.54V
2
(b)
(c)
94.
 aq  and Br (aq),E
Ag  aq  and Cu s  ,EoCu
3
Fe

o
Fe3 /Fe2
2
/Cu
 0.77V; EoBr /2Br  1.07V
2
 0.34V;E
o
Ag /Ag
 0.8V
State the relationship amongst cell constant of a cell. Resistance of the solution in the cell and conductivity
of the solution. How is molar conductivity of a solute related to conductivity of its solution?
95.
Describe the composition of anode and cathode in a mercury cell. Write the electrode reactions for this cell.
Why it provides constant voltage throughout its life?
96.
Give reasons for:
(a) For a weak electrolyte, its molar conductivity of dilute solution increases sharply as the concentration
of solution is decreased.
97.
98.
(b)
Molar conductivity of a strong electrolyte like KCl decrease slightly while increasing concentration?
(c)
It is not easy to determine o m of a weak electrolyte by extrapolation of
c vs m curves?
List two disadvantages of corrosion. Describe the following methods of prevention of corrosion.
(a)
Electrochemical method (cathode protection)
(b)
Covering the surface by other metal. [Sacrificial Protection]
Formulate the galvanic cell in which the following reaction takes place:
Zn s  2Ag aq 
Zn2 (aq)  2Ag(s)
State
(a) Which one of its electrodes in negativity charged?
99.
(b)
The reaction taking place at each of its electrode.
(c)
The direction of current this cell.
The standard reduction potentials are as given below:Half cell
Eo Value
Zn(OH)2/Zn
-1.245 V
Mg(OH)2/Mg
-2.690 V
Fe (OH)2/Fe
-0.877 V
Fe (OH)3/Fe
-2.30 V
Page 26
Under standard conditions:
(a)
Which is the strongest reducing agent?
(b)
Which reducing agent could reduce Zn(OH)2 to Zn?
(c)
Which reducing agent could reduce Fe(OH) 2 to Fe?
100. (a)
(b)
Explain with example the terms weak and strong electrolyres.
Calculate the emf of the cell
Given Mg | Mg2 0.001M || Cu2 0.0001M | Cu
EoCu2 /Cu  0.34V;EoMg2 /Mg  2.375V
101. (a)
(b)
Explain Kohlrausch‟s law of independent migration of ions. Mention two application of this law.
The conductivity of 0.001 M CH 3COOH is 4.95105 Scm1 . Calculate its dissociation constant.
Given for acetic acid o m is 390.5 S cm2 mol-1.
102. (i)
(ii)
Ans.2.651 V
Ans.   0.126
Define molar conductivity. How does it vary with temperature?
Resistance of a solution (A) is 50 ohm and that of solution (B) is 100 ohm, both solution being take in
the same conductivity cell, if equal volumes of solutions (A) and (B) are mixed, what will be the
resistance of the mixture using the same cell? Assume that there is not increase in the degree of
dissociation of (A) and (B) on mixing.
Ans. 66.66 ohm
[Hint : K = Conductivity y = cell constant]
k1 
k k
1
1
y,k2 
y: Specific conductance of mixture  1 2
50
100
2
1 y
y  4
k1  k2 1
  y  R  66.66 ohm
 y  
2
R
2  50 100  R
103. (a)
(b)
Explain Faraday‟s first and second law of electrolysis.
Silver is deposited on a metallic vessel of surface area 800 cm2 by passing current of 0.2 ampere, for
3 hours. Calculate the thickness of silver deposited.
(Density of silver 10.47 g cm-3, atomic mass of silver = 107.924 g mol-1]
104. (a)
(b)
Ans: 2.9 104 cm
Describe the construction and working of standard hydrogen electrode.
Calculate the equilibrium constant for reaction:
Fe2  Ce4
Ce3  Fe3
o
o
Given ECe4 /Ce3  1.44V;EFe3 /Fe2  0.68V
Ans. 7.6 1012
105. The emf of the following cells are:
Ag | Ag 1M || Cu2 1M | Cu, Eo  0.46V
zn | Zn2 1M || Cu2 1M | Cu, Eo 1.1V
Calculate emf of the cell
Zn(s) | Zn2 1M || Ag 1M | Ag s
Ans. 0.64 V
Page 27
106. For concentration cell
Cu s | Cu2 0.01M || Cu2 0.1M | Cu s
(a)
Calculate the cell potential
(b)
Will the cell generate emf when concentration becomes equal.
Ans. 0.295V, No
107. Calculate the equilibrium constant for the reaction at 25 C.
o
Cu(s) +2Ag+ (aq) → Cu2+(aq)+2Ag(s)
Ans. 4.0 1015
The standard cell potential for the reaction at 25oC is 0.46 V.
108. Calculate
Go for the reaction.
Cu2  aq  Fe s 
Fe2 aq  Cu s
EoCu2 /Cu  0.34V; EoFe2 /Fe  0.44V
Ans. 150,540kJ
109. Conductivity of two electrolytic solutions of 0.1 M concentration of the substance A and B are
9.2 103 and 4.7 104 Scm1, which one of these offer less resistance for the flow of current and which
one is a stronger electrolyte?
110. Write the Nernst equation and calculate the emf of the following cell at 298 K.
Cu s  | Cu2  0.130M || Ag 102 M | Ag s 
Given EoCu2 /Cu  0.34V; EoAg /Ag  0.80v
Ans. 0.25V
111. A zinc rod is dipped is 0.1 M solution of ZnSO 4. The salt is 95% dissociated at this dilution at 298K
E
o
Zn2 /Zn
calculate the electrode potential
112. For the electrode Pt, H 2 (1 atm) | H
+

 0.76V .
Ans. 0.7902V
(XM), the reduction electrode potential at 25o C is -0.34V write the
electrode reaction equation and calculate the value of X, How will you deduce the pH of solution from this
(aq)
Ans. X  1.807 106 ,pH  5.743
result?
113. For what concentration of Ag
+
(aq) will the emf of the given cell be zero at 25oC if concentration of
o
 0.34V cell: Cu s / Cu2 (aq) / /Ag aq / Ag(s)
Cu2+(aq) is 0.1M? given EoAg /Ag  0.80V.ECu
2
/Cu
Ans. 5.3109
114. Zinc granules are added in excess to 500 mL of 1.0 M nickel nitrate solution at 25 C unit the equilibrium is
o
reached. If the standard reduction potential of Zn2+ |Zn and Ni2| Ni are -0.75 V and – 0.24 V respectively,
Ans. 5.881018 M
find out the concentration of Ni2+ in solution at equilibrium.
115. The molar conductivity of 0.1 M CH3COOH solution is 4.6S cm
2
Ans. 0.00046Scm1,2174 cm
resistivity of the solution.
116. The molar conductivities of NH
mol-1 calculate the conductivity and
+
4
ion and Cl- ion are 73.5 S cm2 mol-1 and 76.255 cm2 mol-1 respectively.
The specific conductivity of 0.1 M NH 4Cl is 1.288 102 Scm1 Calculate the dissociation constant of
NH4Cl.
Ans. 7.396 102
117. Molar conductivity at infinite dilution for NH 4Cl, NaOH and NaCl solution at 298 K are respectively 129.8,
218.4 and 108 Scm2 mol-1 and m for 10-2 M solution of NH4OH is 9.33 Scm2 mol-1. Calculate the degree
of dissociation of NH4OH.
Ans. 0.039
Page 28
AMINE
Each Question carries 1 Mark
1.
Write a chemical reaction in which iodide ion replaces the diazonium group in diazonium salt.
2.
Arrange the following in increasing order of their basic strength
C6H5NH2, NH3, (C2H5)3NH2, C2H5NH2
3.
Write the chemical equation for the following reaction :
A primary amine is prepared from a primary alkyl halide.
4.
Give a chemical test to distinguish between aniline and N-methylaniline.
5.
Give a chemical test to distinguish between aniline and ethylamine.
6.
Why are aqueous solutions of amines basic in nature?
7.
State the reaction taking place when :
Bromine water is added to the aqueous solution of aniline.
8.
What is Hinsberg reagent?
9.
Complete the following reaction :
10.
Why does acetylation of -NH2 group of aniline reduce its activating effect?
11.
Write IUPAC name of the following compound :

C6H5 N(CH3 )3 Br 
12.
Write the IUPAC name of the following compound :
13.
Account for the following :
Aniline is a weaker base than cyclohexy-lamine.
14.
NH
Br2 /KOH
A 
B
Identify A and B in the following sequence : CH 3COOC2H5 3
15.
Account for the following :
Ammonolysis of alkyl halide does not give a corresponding amine in pure state.
16.
Why do primary amines have higher boiling point than tertiary amine?
Each Question carries 2 Marks
17.
Account for the following :
Amines are basic substances while amides are neutral.
Page 29
18.
(a) Assign a reason for the following statements :
Alkylamines are stronger bases than arylamines.
(b) How would you convert methylamine into ethylamine ?
19.
(a) How will you convert an alkyl halide to a primary amine whose molecule has one more carbon atom
than the used alkyl halide molecule?
(b) Why are amines more basic than the comparable alcohols?
20.
Give reasons :
(a) Methylamine in water reacts with ferric chloride to precipitate ferric hydroxide.
21.
Write one chemical equation each to exemplify the following reaction : Carbylamine reaction.
22.
Illustrate the following with an example of reaction:
(i)
23.
(ii) Hinsberg test.
Illustrate the following with an example of reaction in each case :
(i)
24.
Ambident nucleophile
Sandmeyer reaction.
(ii) Coupling reaction.
Give the structures of A, B and C in following reactions

NaCl
OH
NaOH
(a) CH3CH2I 
A 
B 
C
partial hydrolysis
Br
2
LiAlH4
KCN
 A 
B
(b) CH3CH2Br 
25.
What happens when : (Write reactions only).
(i)
Nitroethane is treated with LiAlH4.
(ii) Diazonium chloride reacts with phenol in basic medium.
Each Question carries 3 Marks
26.
Complete the following chemical reactions :
(i)

OH
C6H5N2Cl + C6H5NH2 


(ii) C6H5 N2Cl  CH3CH2OH 

(iii) RNH2 + CHCl3 + KOH 
27.
State the reactions and reaction conditions for the following conversions :
(i)
Benzene diazonium chloride to nitrobenzene.
(ii) Aniline to benzene diazonium chloride.
(iii) Ethyl amide to methylamine.
28.
How would you achieve the following conversions :
(i)
Nitrobenzene to aniline
(ii) An alkyl halide to a quaternary ammonium salt
(iii) Aniline to benzonitrile
Write the chemical equation with reaction conditions in each case.
29.
Explain the following observations :
(a) Electrophilic substitution in case of aromatic amines takes place more readily than benzene.
(b) Mention two important uses of N, N-Dimethylamine (DMA).
30.
(i)
Stating the necessary reaction conditions write chemical reaction equations to obtain the following :
Chlorobenzene from aniline.
Page 30
(ii) Identify A and B in the following :
31.
Identify A and B in the following reactions :
Each Question carries 5 Marks
32.
(A) Show how p-aminobenzene can be obtained from aniline.
(B) Write structures for the following compounds :
(a) Benzene diazonium chloride
(b) p-Nitrotoluene
(c) Sulphanilic acid
33.
(A) Account for the following :
(i) Aniline is weaker base than methylamine.
(ii) Aryl cyanides cannot be formed by the reaction of aryl halides and sodium cyanide.
(B) How will you convert 4-nitrotoluene tor 2-bromobenzoic acid?
34.
(1) How will you convert:
(a) Nitrobenzene to phenol,
(b) Aniline to chlorobenzene
Identify the compounds A, B and C in the following reactions :
Br2
HNO2
Red P
(2) (a) A 
B 
C 
CH3I
NaOH
I
2
dil.HNO3
NaNO2 HCl
Sn/HCl
B 
C 


(b) A 
Boil
Br2
HNO2

B 
C 

(c) A 
KOH
Page 31
PREVIOUS YEAR BOARD QUESTIONS + HOTS
35.
(i)
Tert-Butylamine cannot be prepared by the action of NH 3 on tert-butyl bromic. Explain why?
(ii) Suggest a convenient method for the preparation of tert-butylamine.
36.
Aman and Rahul took organic
compound synthesis
as
their
chemistry project. They prepare
benzenediazonium chloride. Aman wants to store it to synthesis dye from it next day but Rahul said we
cannot store it and need to use immediately after preparation.
(a) Write the chemical reaction involved in the synthesis of benzene diazonium chloride.
(b) How we cannot store benzenediazonium chloride at room temperature?
(c) Mention the values exhibited by Rahul.
37.
Ram Singh and his friends are playing Holi in their group housing society with natural colours some of his
friends come to play with synthetic colours containing dyes. Pankaj persuades them to play Holi with
natural colours. Ram Singh brother tells them that last year he had developed skin allergy after playing Holi
with synthetic colours and it took him a long time to recover. Ram singh‟s friends agreed to play Holi with
natural ^ colours.
(a) Name the chemical reaction used for the synthesis of azo dye.
(b) Write the chemical reaction for the synthesis azo dye.
(c) Mention the values exhibited by Ram singh and his brother.
38.
Now these days hospital waste management is a big problem. In a hospital corrosive sublimate (HgCl2) is
generally used as a cleansing agent as well as powerful disinfectant. A new CEO Dr. Anil Goel joined the
hospital and suggested the use of quaternary ammonium salts obtained from long chain amine.
(a) Give an example of salt of quaternary ammonium salt which can be used as cationic detergents.
(b) Do you agree with Dr. Anil Goel. If yes, then explain why?
(c) Mention the values associated with Dr. Anil Goel‟s advice.
39.
(a) Write structures of different isomeric amines corresponding to the molecular formula, C4H11N.
(b) Write IUPAC names of all the isomers.
(c) What type of isomerism is exhibited by different pairs of amines?
40.
Write structures and IUPAC names of :
(i)
the amide which gives propanamine by Hoffmann bromamide reaction.
(ii) the amine produced by the Hoffmann degradation of benzamide.
41.
How will you convert:
(i)
Benzene into aniline?
(ii) Benzene into N, N-dimethylaniline
(iii) Cl  (CH2 )4  Cl into hexan-1, 6-diamine?
42.
Arrange the following in increasing order of their basic strength :
(a) C2H5 NH2 , C6H5 NH2 , NH3 , C6H5CH2 NH2 and (C2H5 )2 NH
(b) C2H5 NH2 , (C2H5 )2 NH, (C2H5 )3 N, C6H5 NH2
(c)
CH3NH2 , (CH3 )2 NH, (CH3 )3 N, C6H5 NH2 , C6H5CH2 NH2
Page 32
43.
Write chemical reaction of aniline with benzoyl chloride and write name of the product obtained.
44.
Write structures of different isomers corresponding to the molecular formula, C 3H9N. Write IUPAC names
of the isomers which will liberate nitrogen gas on treatment with nitrous acid.
45.
How will you convert 4-nitrotoluene to 2-bromobenzoic acid?
46.
Give one chemical test to distinguish between the following pairs of compounds :
(i)
Methylamine and dimethylamine
(iii) Ethylamine and aniline
(ii) Secondary and tertiary amines
(iv) Aniline and benzylamine
(v) Aniline and N-methylaniline
47.
Account for the following :
(i)
pKb of aniline is more than that of methylamine.
(ii) Ethylamine is soluble in water, whereas aniline is not.
(iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.
(iv) Although amino group is o- and p- directing in aromatic electrophilic substitution reactions, aniline on
nitration gives a substantial amount of m-nitroaniline.
(v) Aniline does not undergo Friedel Crafts reaction.
(vi) Diazonium salts of aromatic amines are more stable than those of aliphatic animes.
(vii) Gabriel phthalimide synthesis is preferred for synthesising primary amines.
48.
How will you convert :
(i)
49.
Ethanoic acid into methanamine,
(ii) Hexanenitrile into 1-aminopentane,
(iii) Methanol to ethanoic acid,
(iv) Ethanamine into methanamine,
(v) Ethanoic acid into propanoic acid,
(vi) Methanamine into ethanamine,
(vii) Nitromethane into dimethylamine,
(viii) Propanoic acid into ethanoic acid?
Describe a method for the identification of primary, secondary and tertiary amines. Also write chemical
equations of the reactions involved.
50.
Write short notes on the following :
(i) Carbylamine reaction
(ii) Diazotisation
(iii) Hoffmann‟s bromamide reaction
(iv) Coupling reaction
(v) Ammonolysis
(vi) Acetylation
(vii) Gabriel phthalimide synthesis
51.
Accomplish the following conversions :
(i)
Nitrobenzene to benzoic acid
(ii) Bezene to m-bromophenol
(iii) Benzoic acid to aniline
(iv) Aniline to 2, 4, 6-tribromofluorobenzene
(v) Benzyl chloride to 2-phenylethanamine
(vi) Chlorobenzene to p-chloroaniline
(vii) Aniline to p-bromoaniline
(viii) Benzamide to toluene
(ix) Aniline to benzyl alcohol
Page 33
52.
Give the structures of A, B and C in the following reactions :
(i)

NaOHBr2
NaCN
OH
CH3CH2I 
A 
B 
C
Partial hydrolysis

NH3
H2O/H
CuCN
(ii) C6H5 N2Cl 
A 

B 

C

LiAlH4
HNO2
KCN
(iii) CH3CH2Br 
 A 
B 
C
0o C

NaNO2 HCl
H2O/H
Fe/HCl
(iv) C6H5 NO2 
A 

 B 

C
273 K

NH3
NaNO2 /HCl
NaOBr
(v) CH3COOH 
 A 
B 
C

C6H5OH
HNO2
Fe/HCl
(vi) C6H5 NO2 
A 
 B 

C
273 K
53.
An aromatic compound „A‟ on treatment with aqueous ammonia and heating forms compound „B‟, which
on heating with Br2 and KOH forms a compound „C‟ of molecular formula C6H7 N . Write the structures
and IUPAC names of compounds A, B and C.
54.
Complete the following reactions :
(i)
C6H5 NH2  CHCl3  alc. KOH 

(ii) C6H5 N2Cl  H3PO2  H2O 

(iii) C6H5 NH2  H2SO4 (conc.) 

(iv) C6H5 N2Cl  C2H5OH 

(v) C6H5 NH2  Br2 (aq) 

(vi) C6H5 NH2  (CH3CO)2 O 

(i) HBF4
(vii) C6H5 N2Cl 

(ii) NaNO /Cu, 
2
55.
Why aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis?
56.
Give plausible explanation for each of the following :
(i)
Why are amines less acidic than alcohols of comparable molecular masses ?
(ii) Why do primary amines have higher boiling point than tertiary amines?
(iii) Why are aliphatic amines stronger bases than aromatic amines?
57.
Write IUPAC names of the following amines :
Page 34
58.
Giving an example of each describe the following reactions :
(i)
Hoffman bromamide reaction
(ii) Gabriel phthalimide synthesis
(iii) Gatterman reaction
(iv) Coupling reaction
(v) Hoffman‟s ammonolysis
(vi) Carbylamine reaction
(vii) Acetylation of aniline.
59.
Describe the method for identification of primary, secondary and tertiary amines. Also write the chemical
equations of the reactions involved.
60.
Arrange the following in the increasing order of given property :
(i)
C2H5NH2, (C2H5)2NH, (C2H5)3N and NH3, (Basic strength in aqueous solution).
(ii) C2H5NH2, (C2H5)2NH, (C2H5)3N and CH3NH2. (Basic strength in gaseous phase).
(iii) Aniline, p-toluidine, p-nitroaniline. (Basic strength).
(iv) NH4+, C6H5NH3+, p-F-C6H5NH3+. (Acid strength).
61.
Identify A and B in the following reactions :
(i)
373 K
CH3CH2Cl + NH3 (Excess) 
A
373 K
(ii) CH3CH2Cl + NH3 

(excess)
62.
How will you bring about the following conversions?
(i) Benzene to Aniline
(ii) Aniline to benzene
(iii) Ethanoic acid to ethanamine
(iv) p-Toluidine to 2-Bromo-4-methylaniline.
(v) Methylbromide to ethanamine
(vi) Benzenediazonium chloride to nitrobenzene
(vii) Ethylamine to methylamine
(viii) Benzene to sulphanilic acid
(ix) Hexanenitrile to 1-aminopentane.
63.
Write the products formed in the following sequence of reactions :
64.
Identify the missing reagent/product in the following reactions :
Page 35
65.
Give one chemical test to distinguish between the following pairs of compounds :
(i)
Methylamine and dimethylamine
(ii) Secondary and tertiary amines
(iii) Ethylamine and aniline
(iv) Aniline and benzylamine
(v) Methylamine and methanol
(vi) Methylamine and N, N-Dimethylamine
(vii) Ethanol and ethanamine
66.
Explain why :
(i)
The C-N-C bond angle in trimethyl amine is 108°
(ii)
The quaternary ammonium salts having four different alkyl groups are optically active
(iii)
Alkylamines are more basic than ammonia
(iv)
Aniline can not be prepared by Gabriel phthalimide synthesis
(v)
Garbriel phthalimide synthesis is preferably used for synthesising primary amines.
(vi)
Ethylamine is soluble in water but aniline is not
(vii)
Aniline is soluble in dilute HCI.
(viii) Amines have lower boiling point than alcohols of comparable molecular masses.
(ix)
1° Amines have higher boiling points than 2° amines which in turn are higher boiling than 3° amines.
(x)
The pKb value of benzeneamine is 9.33 while that of ammonia is 4.75.
(xi)
Aniline does not undergo Friedel Crafts reaction.
(xii)
Aniline readily forms 2, 4, 6-tribronoaniline on reaction with bromine water.
(xiii) Sulphanillic and is soluble in water.
(xiv) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.
(xv) Diazonium salt of aromatic amines are more stable than the diazonium salts of aliphatic amines.
(xvi) Although amino group is o, p-directing in aromatic electrophilic substitution reactions, aniline on
nitration gives a substantial amount of m-nitroaniline.
67.
Why do amines act as nucleophiles? Give example of a reaction in which methylamine acts as a nucleophile.
68.
Why does diazonium ion act as an electrophile? Give example of a reaction where diazonium ion acts as an
electrophile.
69.
Three isomeric amines A, B and C have the molecular formula C 3H9N. Compound A on reaction with
benzene sulphonyl chloride forms a product which is soluble in NaOH. Compound B on reaction with
benzene sulphonyl chloride forms a product which is insoluble in NaOH and compound C does not react
with benzene sulphonyl chloride. Identify A, B and C.
[Ans. : A = CH3CH2CH2NH2
70.
An organic compound A (C2H3N) is used as a solvent of choice for many organic reactions because it is not
reactive in mild acidic and basic conditions. Compound A on treatment with Ni/ H 2 forms B. When B is
treated with nitrous acid at 273K ethanol is obtained. When B is warmed with chloroform and NaOH a foul
smelling compound C formed. Identify A, B and C.
[Ans. : A = CH3 C
71.
B = CH3CH2NHCH3 C = (CH3)3N]
 N, B = CH3CH2NH2, C = CH3CH2N  C
An organic compound [A] C3H6O2 on reaction wish ammonia followed by heating yield B. Compound B on
reaction with Br2 and ale. NaOH gives compound C, (C2H7N). Compound C forms a foul smelling
compound D on reaction with chloroform and NaOH. Identify A, B, C, D and the write the equations of
reactions involved.
[Hint : A = CH3CH2COOH, B = CH2CH2CONH2, C = CH3CH2NH2, D = CH3CH2NC.]
Page 36
CHEMICAL KINETICS
Each Question carries 1 Mark
Ans. k 
[R]
2.303
log 0
t
[R]
1.
How will you prove that a chemical reaction is of first order?
2.
The reaction A  B 
 C has zero order. What is the rate equation?
3.
What is meant by elementary step in a reaction?
4.
Express the rate of the following reaction in terms of disappearance of hydrogen in the reaction.
Ans. Rate = k
3H2 (g)  N2 (g) 
 2NH3 (g)
5.
Define order of reaction.
6.
What is the order of reaction in following reaction? Rate  k[A]1/2 [B]3/2 .
7.
For a chemical reaction, what is the effect of catalyst on the rate of the reaction.
8.
Why does the rate of reaction not remain constant throughout the reaction process?
9.
Identify the order of reaction from the following rate constant : k  2.3  105 L mol1 s1
10.
If half life period of a first order reaction is X and
Ans. = 2
3
th life period of the same reaction is Y, how are x and
4
Ans. y  2x
y related each other?
11.
What is activation energy?
12.
For a chemical reaction, what is the effect of a catalyst on activation energy of a reaction.
13.
For a chemical reaction R - P, the variation in the concentration (R) vs time (t) plot is given as. What is the
slope of the curve?
14.
Express the relation between the half life period of a reaction and initial concentration of the reaction of
second order.
15.
Ans. = - k
Ans. = t1/2 
1
[R]0
What is molecularity?
Each Question carries 2 Marks
16.
Define rate law. Give example.
17.
At 300oC the thermal dissociation of HI is found to be 20%. What will be the equilibrium concentration of
 2HI at this temperature if the equilibrium concentration of HI in it be
H2 and I2 in the system H2  I2 
0.96 mol L-1 ?
Ans. = 0.12 mol
Page 37
18.
Define zero order reaction. Give its unit.
19.
Distinguish between molecularity and order of reaction.
20.
A reaction is of second order with respect to a reactant. Now, is its rate affected if the concentration of
reactant is (i) doubled (ii) reduced to half
21.
Explain the terms:
(i)
Rate determining step of a reaction.
(ii) Pseudo first order reaction.
22.
Explain the differences between the average rate and instantaneous rate of a chemical reaction.
23.
State the role of activated complex in a reaction and state its relation with activation energy.
24.
With the help of a diagram, explain the physical significance of energy of activation (Ea ) in chemical
reactions.
25.
Distinguish between rate expression and rate constant of a reaction.
26.
Calcualte the half life of first order reaction whose rate constant is 200 s -1.
27.
Derive the general form of expression of the half life of first order reaction.
28.
The rate constant for a zero order reaction is 0.0039 mol L -1 s-1. How long will it take for the initial
concentration of reactant A fall from 0.10 M to 0.075 M?
Each Question carries 3 Marks
29.
The data given below is for the reaction, 2N2O5 (g) 
 4NO2 (g)  O2 (g)
S. No.
N2O5 (mol L-1)
Rate of disappearance of N 2O5 (mol L-1 min-1)
1.
1.13  102
34  105
2.
0.84  102
25  105
3.
0.62  102
18  105
Determine for this reaction,
(i)
30.
Order of reaction
(ii) Rate law
(iii) Rate constant
C  D
The following results have been obtained during kinetic studies of the reaction : 2A  B 
Exp. No.
[A]
[B]
Initial rate of Formation of D
1.
0.1 M
0.1 M
6.0  103 M min 1
2.
0.3 M
0.2 M
7.2  103 M min 1
3.
0.3 M
0.4 M
2.88  103 M min 1
4.
0.4 M
0.1 M
2.40  103 M min 1
Determine rate law and the rate constant for the reaction.
31.
C  D
Consider the reaction 2A  B 
Following results were obtained in experiments designed to study the rate of reaction :
Page 38
Initial concentration (mol L-1)
Exp. No.
(i)
Initial rate of formation
[B]
0.10
[D] (m/min)
1.
[A]
0.10
2.
0.20
0.20
3.0  103
3.
0.20
0.40
6.0  103
1.5  103
Write the rate law for the reaction.
(ii) Calculate the value of rate constant for the reaction.
(iii) Which of the following possible reaction mechanism is consistent with the rate law ?
I.
A  B 
C E
(slow)
A  E 
D
(fast)
B 
C  E
II.
A  E 
F
(slow)
(fast)
32.
A  F 
D
(fast)
A first order reaction is 15% complete in 20 minutes. How long will it take to be 60% complete?
33.
Prove that the time required for the completion of
3
of the first order is twice the time required for the
4
completion of half of the reaction.
34.
Show that in case of first order reaction, the time required for 99.9% of the reaction to complete its 10 times
that required for half of the reaction to take place. (Given : log 2 = 0.3010)
35.
The rate constant for a first order reaction is 60 s -1. How much time will it take to reduce the concentration
of the reactant to
36.
1
th of its initial value?
10
Ans. = 0.0384 s.
The half life for a first order reaction is 5  104 s . What percentage of the initial reactant will react in 2
hours?
37.
A first order reaction has a rate constant value of 0.00510 min-1. If we begin with 0.10 M concentration of
the reactant, how much of the reactant will remain after 3.0 hours?
38.
Ans. = 0.04 M.
Hydrogen peroxide, H2O2(aq) decomposes to H2O (l) and O2 (g) in a reaction that is of first order in H 2O2
and has a rate constant, k  1.06  103 min 1 .
(i)
How long will it take 15% of a sample of H 2O to decompose?
(ii) How long will it take 85% of a sample of H 2O2 to decompose?
39.
The decomposition of phosphine PH 3 proceeds according to the following equation:
4PH3 (g) 
 P4 (g)  6H2 (g)
It is found that the reaction follows the following rate equation Rate = k [PH 3]
The half life of PH3 is 37.9 s at 20oC.
(i)
How much time is required for
3
th of PH3 to decompose? PH3 remains behind after 1 minute?
4
(ii) What fraction of the original sample of PH 3 remains behind after 1 minute?
Page 39
40.
The decomposition of a compound is found to follow at first order rate law. If it takes 15 minutes for 20
percent of original material to react, calculate:
(i)
41.
the rate constant.
(ii) the time at which 10% of the original material remains unreacted.
In a pseudo first order hydrolysis of ester in water, the following results are obtained :
(i)
t(in seconds)
0
30
60
90
[Ester] M
0.55
0.31
0.17
0.085
Calculate the average rate of reaction between the time interval 30 to 60 s.
(ii) Calculate the pseudo first order rate constant for the hydrolysis of ester.
Each Question carries 5 Marks
42.
(a) Derive the general form of the expression for the half life of a first order reaction.
(b) Nitrogen pentoxide decomposes according to the equation 2N2O5 (g) 
 4NO2 (g)  O2 (g)
This first order reaction was allowed to proceed at 40oC and the data given below:
(i)
[N2O5] [M]
0.400
Time (min)
0.00
0.289
20.0
0.209
40.0
0.151
60.0
0.109
80.0
Calculate the rate constant. Include units with your answer.
(ii) What will be the concentration of N 2O5 after 100 min?
(iii) Calculate the initial rate of reaction.
43.
(a) What is the significance of negative sign in the rate expression in term of reactants?
(b) The decomposition of a compound is found to follow a first order rate law. If it takes 15 min. for 20% of
original material to react, calculate : (i) the specific rate constant, (ii) the time at which 10% of the
original material remains unreacted, (iii) the time it takes for the next 20% the reactant left to react after
the first 15 min.
44.
(a) The initial rate of reaction, A + B 
 products, is doubled when the initial concentration of A is
doubled and increases eight fold when the initial concentration of both A and B are doubled. State the
order of the reaction with respect to A and B. Write the rate equation.
(b) The data given below is for the reaction :
Expt. No.
[N2O5] (mol L-1)
Rate of disappearance of [N 2O5] (mol L-1)
1.
1.13  102
34  105
2.
0.84  102
25  105
3.
0.62  102
10  105
Determine :
(i)
Order of reaction.
(ii) Rate constant.
(iii) Rate law.
Page 40
PREVIOUS YEAR BOARD QUESTIONS + HOTS
45.
The rate of decomposition of ammonia is found upon the concentration of NH 3 according to the equation :
d[NH3 ]
k [NH3 ]
 1
dt
1  k 2[NH3 ]
What will be the order of reaction when :
(i)
46.
concentration of NH3 is very high?
(ii) concentration of NH3 is very low?
k
Consider the reaction A 
 P. The change in concentration of A with time is shown in the plot.
(i)
Predict the order of the reaction.
(ii) Derive the expression for the time required for the completion of the reaction.
47.
Give two examples of non-chemical process which obeys the first order kinetics.
48.
Prove mathematically that the time required for the completion of any fraction of first order kinetics is
independent of initial concentration of reactant.
49.
Ans. t1/2 
2.303
n
log
k
n 1
Prakash is a student of class XII science. He is preparing oxygen gas in laboratory by heating KClO 3. His
friend sachin suggested him to use MnO 2 as a catalyst to get higher yield of oxygen readily. Actually
catalyst provide an alternative route and reaction becomes faster.
(a) How catalyst increases the rate of reaction? Explain graphically.
(b) Define activation energy.
(c) Mention the values exhibited by Sachin.
50.
Mansh went to market to buy fruit and vegetables. He was attracted to buy fruit and vegetables which were
big in size. When he reached home, his mother told him that he had not brought good quality stuff. She
explained to him that these had been grown to this size by using synthetic fertilizers and pesticides which
are harmful for our health. After reading the above paragraph, answer the following questions :
(a) What values have been expressed in the above paragraph?
51.
How and why fertilizers and pesticides are harmful to human health. What solution do you suggest to the
problem?
52.
While walking on the footpath, sometimes some autos pass on the road which exhaust a lot of smoke and
gases causing pollution and we feel suffocated. Meenu discussed the problem with her teacher as to why
these vehicles caused pollution. The teacher explained to her that exhaust pipes of some vehicles are not
fitted with good quality catalytic convertors or people don‟t get the service of their vehicle done at regular
times.
Page 41
Now, answer the following questions:
(a) What values are expressed in the above paragraph?
(b) How catalytic convertors fitted in the exhaust pipe help in reducing pollution?
53.
Define the term „rate of reaction‟.
54.
Mention the units of rate of reaction.
55.
Express the rate of reaction in terms of Br (aq) as reactant and Br 2 (aq) as product for the reaction:
5Br aq  BrO3 aq  6H aq 
3Br2 aq  3H2Ol
56.
For a chemical reaction represented by R  P the rate of reaction is denoted by
Why a positive sign (+) is placed before
57.
R
P
or
t
t
  P
R 
and not before
?
t
t
Express the rate of reaction in terms of disappearance of hydrogen and appearance of ammonia in the given
reaction. N2 g  3H2 g 
2NH3 g
58.
Why rate of reaction does not remain constant throughout?
59.
Write the unit of first order rate constant of gaseous reaction if the partial pressure of gaseous reactant is
[Ans. atm s -1]
given in atm.
60.
For a zero order reaction:
R 
P, the change in concentration of reactant w.r.t. time is shown by following graph.
What does the slope of the graph represent?
61.
A0  A  k
slope  k0
0   A   A0  k 0 t
t
What will be the order of reaction, if the rate of reaction does not depend on the concentration of any of the
Hint :
reactant.
62.
For the elementary step of a chemical reaction:
A  H2O 
B
Rate A
1
What is the (i) Molecularity and (ii) order of the reaction.
[Ans: (i) 2 (ii) 1]
63.
For a chemical reaction AB. The rate of the reaction is given as rate = k[A] n
64.
The rate of the above reaction quadruples when the concentration of A is doubled. What is the value of n?
[Ans : n =2]
Mention one example of zero order reaction.
65.
What is the value of the order of reaction of an artificial radioactive decay?
[Ans: First order]
Page 42
66.
Express the relation between the half life period of a reactant and initial concentration for a reaction of nth

[Ans: t1/2
order.

1 

A0n1 
67.
A reaction is 50% complete in 2 hours and 75% complete in 4 hours. What is the order of reaction?
68.
What is the source of activation energy in a photochemical reaction?
69.
Suggest an appropriate reason for the observation: “ on increasing temperature of the reacting system by 10
degrees, the rate of reaction doubles or even some times becomes five folds.”
70.
For a chemical reaction activation energy is zero and at 300 K rate constant is 5.9 105 sec1 . what will be
[Ans: 5.9 105 sec1 . ]
the rate constant at 400k?
71.
Two reactions have identical values of Ea. Does this ensure that they will have the same rate constant if run
at the same temperature? Explain.
72.
The rate constant of a reaction is given by the expression k  AeEa/RT
Which factor in this expression should register a decrease so that the reaction proceeds rapidly?
73.
For a chemical reaction rate constant k  5.3 104 mol L1 s1 what will be the order of reaction?
74.
Write the rate law and order for the following reaction:
AB2  C2 
AB2C  CSlow
[Ans: Rate  kAB2 C2 ; Order  1 1  2]
AB2  C 
AB2C Fast 
Each Question carries 2 Marks
75.
List four factors which affect the rate of a chemical reaction. State how each of these factors changes the
reaction rate.
76.
Differentiate between
(a) Average rate and instantaneous rate of a chemical reaction.
(b) Rate of a reaction and specific rate of reaction.
77.
The rate law for the reaction A + B P is given by
Rate : k A B
n
m
On doubling the concentration of A and reducing the concentration of B to half of its original concentration,
calculate the ratio of the new rate to the previous rate of reaction.
78.
[Ans : 2 n-m]
For the reaction in a closed vessel:
2NOg  O2 g 
2NO2 g; Rate  kNO O2 
2
If the volume of the reaction vessel is doubled, how would it affect the rate of the reaction?
[Ans: Diminish to 1/8 volume of initial value]
79.
Explain with an example, what is a pseudo first order reaction?
80.
Show that time required for 99.9% completion of the first order reaction is 10 times of t 1/2 for first order
chemical reaction.
Page 43
81.
The graphs (1 and 2) given below are plots of rate of reaction verses concentration of the reaction predict
the order from the graphs.
82.
(a) For a reaction A + B  Products, the rate law is given by r  k A
1/2
B2
What is the order of reaction.
(b) The conversion X to Y follows second order kinetics. If concentration of X is increased to three times
how will it affect the rate of formation of Y?
83.
[Ans : (a) 5/2; (b) 9 times]
Gaseous phase decomposition of N 2O is given below.
Step I : N2Og 
N2 g  Og
Step II: N2Og  Og 
N2 g  O2 g
(a) Write a chemical equation for overall reaction.
(b) Identify the reaction intermediate.
(c) What is the molecularity of each of the elementary reaction?
(d) What is the molecularity of the overall reaction?
84.
The possible mechanism for the reaction
2NOg  O2 g 
2NO2 gis
(a) NO  O2
k
NO3 Slow
k1
NO2  NO2  Fast 
(b) NO3  NO 
What is the predicted rate law and order of the reaction?
[Ans : Rate  k NO O2 ; Order  2 1  3]
2
Each Question carries 3 Marks
85.
What is meant by zero order reaction? Derive an integrated rate equation for a zero order reaction.
86.
(a) Write four points of difference between order and molecularity of a reactions?
(b) List four method for determination of order of reactions?
87.
Explain the following:
(a) A lump of coal burns at moderate rate in air while coal dust burns explosively.
(b) Average rate of reaction does not give the true picture of the reaction.
(c) Reactions of high molecularity are less in number?
Page 44
88.
Draw a graph between fraction of molecules and kinetic energy of the reacting species for two different
temperatures.
(a) Room temperature
(b) Temperature 10oC higher than the room temperature
(c) Indicate the fraction of additional molecules which react at  t 10 C.
o
89.
The energy of activation for forward and backward reactions for a hypothetical
reaction P  Q are 15 kJ/mol respectively. Potential energy of P is 10 kJ/mol as
shown in the graph. Predict.
(a) Threshold energy of the forward reaction.
(b) Potential energy of Q.
(c) Heat of reaction.
[Ans: (a) 25 kJ (b) kJ (c) 6 kJ]
Each Question carries 5 Marks
90.
(a) A chemical reaction is of second order w.r.t. a reactant. How will the rate of reaction be affected if the
concentration of this reactant is : (a) Doubled ; (b) Reduced to 1/8 th.
[Ans ; (a) Four times (b) 1/64]
(b) From the following data for a chemical reaction between A and B at 300 K
[A] mol/L
[B] mol/L
Initial rate (mol L-1 sec -1)
2.5104
3105
5 104
2.5104
6 105
4 103
1103
6 105
1.6 102
Calculate (i) the order of reaction with respect to A and with respect to B. (ii) the rate constant at 300 K.
91.
(a) Define the terms
(i)
Temperature co-efficient of a reaction
(ii) energy of activation
(b) The energy of activation for a chemical reaction is 100 kj/mol. Presence of a catalyst lowers the energy of
activation by 75%. What will be effect on the rate of reaction at 20oC, if other things are equal.
92.
(a) Derive the equation for rate constant of a first order reaction. What would be the units of the first order
rate constant if the concentration is expressed in moles per litre and time in second?
(b) For first order chemical reaction half life period
 t1/2  is concentration
independent.
Justify the statement by using integrated rate equation.
93.
k
SO2 g  Cl2 g is a first order reaction with half life of 3.15 104 s at 575 K.
The reaction SO2Cl2 g 
what percentage of SO2Cl2 would be decomposed on heating at 575 K for 90 min.
94.
[Ans. 11.2%]
A certain reaction is 50% complete in 20 min at 300 K and the same reaction is again 50% complete in 5
min at 350K. calculate the activation energy if it is a first order reaction.
R  8.314 JK
mol1.log4  0.602
1
[Ans : 24.206 kJ/mol]
Page 45
95.
For a chemical reaction AB, it was found that concentration of B increase by 0.2 mol L -1 in half an hour.
What is the average rate of reaction.
[Ans: 0.0066 mol L-1 min-1]
96.
In the reaction R  P, the concentration of R decreases from 0.03M to 0.02 M in 25 minutes calculate the
average rate of reaction using unit of time both in minutes and seconds.
[Ans. 4 104 M min 1 ,6.66 106 M s1 ]
97.
A first order reaction has a rate constant 1.15 103 s1. how long will 5g of this reactant take to reduce to 3g?
[Ans: t  444s]
98.
The rate of reaction triples when the temperature changes from 20oC to 50oC. calculate the energy of
activation. R  8.314Jk1m kol1,log 3  0.48
99.
[Ans: 12.59 kJ]
A first order reaction was started with a decimolar solution of the reactant. 8 minutes and 20 seconds later
its concentration was found to be
M
. calculate the rate constant of the reaction.
1000

R0 .
M
M
2.303
 0.001M. Apply k 
log
Hint : R 0   0.1M;R 500 
10
100
t
R 

100.
A hydrogenation reaction is carried out at 550 K. if the same reaction is carried out in the presence of a
catalyst at the same rate, the temperature required is 400 K. calculate the activation energy of the reaction if
the catalyst lowers the activation barrier by 20 kJ mol-1.
[Hint: k  AeEa/RT in the absence of catalyst, Ea  x kJmol1. in the presence of catalyst. Ea   x  20 kJ mol1 ]
[Ans : Ea  100 KJ mol1 ]
101.
The rate constant for the first order decomposition of H 2O2 is given by the following equation log
k  14.34 1.25104 K / T . Calculate Ea for this reaction and at what temperature will its half. Life be 256
minutes.
[Ans. Ea  239.34kJ;T  670k]
102.
Show that for a first order reaction, time required for 99% completion is twice for the time required for the
completion of 90% of reaction.
103.
2AB, are as follows. Write probable rate expression.
The experimental data for the reaction 2A + B 2 
104.
[A] mol/-1
0.5
[B 2] mol/L-1
0.5
0.5
1.0
1.0
1.0
Initial rate mol L-1 sec-1
1.6 104
3.2 104
3.2 104
dx
 k B2 
dt
A reaction is 20% complete in 20 minutes. Calculate the time required for 80% completion of reaction, if
reaction follows the first order kinetics.
105.
[Ans.
[Ans : 144 min]
P4 g  6H2 g has rate law: Rate  k PH3  . The rate
The decomposition of phosphine 4PH3 g 
constant is 6.0 104 s1 at 300K and activation energy is 3.05 106 J mol1 . Calculate the value of the rate


constant at 310K. R  8.314 Jk1mol1 .
106.
[Ans. 30.97 103 s1 ]
For the decomposition of azoisopropane to hexane and nitrogen at 543K, the following data is obtained.
t sec.
0
360
720
Pressure (atm).
35.0
54.0
63.0
Calculate the rate constant.
[Ans. k360  2.17 103 s1; k720  2.24 103 s1 ]
Page 46
p-Block
Each Question carries 1 Mark
1.
Nitric oxide becomes brown when released in air, why?
2.
Write chemical equation involved in preparation of H 3PO3.
3.
Why is red phosphorus less reactive than white phosphorus?
4.
Complete the chemical equation: Cu2+(aq) + NH3(aq) 

5.
Nitrogen does not form pentahalides. Why?
6.
How can ammonia reacts with a solution of Cu2+?
7.
Arrange the following in order of the increasing basic strength : PH 3, NH3, BiH3, SbH3, AsH3
8.
Complete the equation : P 4 + NaOH + H2O 

9.
Explain Haber‟s process conditions.
10.
Draw molecular structure of N 2O5.
11.
Complete the following equation : Cu  HNO3 (dilute) 

12.
Draw structure of H 3PO2.
13.
Complete the equation : PCl5 + H2O (excess) 

14.
Why does NO2 dimerise?
15.
Complete the following reaction : NH 3 + NaOCl 

16.
Nitrogen shows weaker tendency for catenation than phosphorus. Why?
Each Question carries 2 Marks
17.
The acidic strength decreases in the order HCl > H 2S > PH3. Why?
18.
What is laughing gas? How is it prepared?
19.
How would you account for the following :
(i)
Sulphur hexafluoride is less reactive than sulphur tetrafluoride.
(ii) Of the noble gases only xenon forms known chemical compounds.
20.
Answer the following questions :
(i)
Which neutral molecule would be isoelectronic with ClO -?
(ii) Of Bi(V) and Sb(V), which may be a stronger oxidising agent and why?
21.
Write the structures of the following compounds :
(i)
22.
H3PO2
(ii)
H2SO5
How would you account for the following?
(i)
Hydrogen fluoride is much less volatile than hydrogen chloride.
(ii) Interhalogen compounds are strong oxidising agents.
Page 47
23.
Write the balanced chemical equations for obtaining XeO 3 and XeOF4 from XeF6.
24.
Complete the following equations :
(a) PCl3 + H2O 

25.

(b) NaN3 

Name the two most important allotropes of sulphur which one of the two is stable at room temperature?
What happens when the stable form is heated above 369 K?
26.
Draw the structures of :
(i)
27.
Hypochlorous acid.
(ii) Chlorous acid.
Assign a reason for each of the following :
(i)
Ammonia is a stronger base than phosphine.
(ii) Sulphur in vapour state exhibits a paramagnetic behaviour.
28.
Complete the following chemical reaction equation :
(i)
29.
I2  HNO3 (Conc.) 

(ii) HgCl2  PH3 

Explain the following observations :
(i)
The molecules NH3 and NF3 have dipole moments which are of opposite direction.
(ii) All the bonds in PCl5 molecule are not equivalent.
Each Question carries 3 Marks
30.
(a) Draw the structural formulae of the following molecules :
(i)
P4O10 (s)
(ii) XeO3(s)
(b) Draw the structural formulae of SF4(g).
31.
Give reasons for the following :
(i)
Addition of Cl2 to KI solution gives it a brown colour, but excess of Cl2 turns it colourless.
(ii) Phosphinic acid behaves as a monoprotic acid.
(iii) White phosphorus is much more reactive than red phosphorus.
32.
(a) What prompted Bartlett to the discovery of noble gas compounds?
(b) State two importance of noble gases.
33.
Write chemical equations for the following processes :
(i)
Chlorine reacts with a hot concentrated solution of sodium hydroxide.
(ii) Orthophosphorus acid is heated.
(iii) PtF6 and Xe are mixed together.
34.
Complete the following chemical equations :

(i) Ca 3P2 (s)  H2O(l ) 

(ii) Cu2+(aq) + NH3(aq) 

(iii) F2(g) + H2O(l) 
Page 48
35.
Arrange the following in order of the property mentioned :
(i)
PH3, NH3, SbH3, AsH3 (increasing basic strength)
(ii) KCl, MgCl2, CaCl2, BaCl2 (increasing ionic character)
(iii) HClO4, HClO, HClO2 (increasing oxidising ability)
36.
Describe the following about halogen family (Group 17 elements) :
(i)
Relative oxidising power.
(ii) Relative strength of their hydrides.
(iii) Oxyacids and their related oxidising ability.
Each Question carries 5 Marks
37.
(i)
Explain the Ostwald‟s process to manufacture nitric acid.
(ii) Write the balanced reaction when nitric acid react with:
(a) I2
(b) C
(c) S8
(d) P 4
(iii) Give any two uses.
38.
How is ammonia manufactured industrially? Draw flow chart for the manufacture of ammonia. Give any
two uses.
39.
(i)
How is sulphur dioxide prepared in :
(a) laboratory
(b) industrially?
(ii) What happens when sulphur dioxide is passed through water and reacts with sodium hydroxide? Write
balanced equation.
(iii) Write its any two uses.
PREVIOUS YEAR BOARD QUESTIONS + HOTS
40.
(a) You have the following substances :
NH3, O, Pt and H2O. Write equations for the preparation of N 2O from these substances.
(b) Considering the fact that N makes-up about 79% of the atmosphere, why don‟t animals use the most
abundant N2 instead of O2 for biological reactions.
41.
Assign reasons for the following :
(i)
When a moist blue litmus paper is dipped in a solution of HCl, it first turns red and then later gets
decolourised. Explain.
(ii) Iodine is liberated when KI is added to the solution of Cu2+ ions but Cl2 is not liberated when KCl is
added to a solution of Cu2+ ions. Why?
(iii) Name a compound of fluorine which shows +1 oxidation state. How is this compound prepared? Is this
a disproportionation reaction?
Page 49
42.
A few students of class XII were playing in the playground under the supervision of their coach. All of a
sudden Priyank fell down. The coach immediately rushed towards Priyank and examined the wound. He
opened up his sporting kit and pulled out a small plastic pack. He squeezed hard the pack and placed it on
the injured portion of his skin. Priyank got some conform and relief. Later coach took Priyank to hospital
for further treatment.
Read the above passage and answer the following questions :
(a) What values were expressed by coach towards Priyank?
(b) Name the chemical contained in the plastic pack. What is this pack called and how does it work?
(c) Name two other uses of the chemical contained in the small plastic pack.
43.
To extract metals, the sulphide ores are first roasted in a reverberatory furnace in excess of air when metal
oxide is formed and sulphur dioxide is released. Sulphur dioxide is a major air pollutant. It produces acid
rain which damages crops, iron structures and buildings/ historical monuments made-up of marble.
Now, answer the following questions :
(a) Name three important sulphide ores.
(b) What is acid rain? How does it damage crops, iron structures and buildings made- up of iron?
(c) As a student of chemistry, what steps do you propose to control air pollution.
44.
Mineral acids such as HNO 3, HCl and H2SO4 are widely used in industry and in the laboratory. In fact,
applications of H2SO4 in industry are so vast that it is actually called King of Chemicals. But unfortunately,
in the recent past, many instances of acid attack by eve teasers and frustrated lovers on the faces of young
girls have been reported in newspapers and shown on TV. This is a serious social evil and must be totally
eliminated from the society.
45.
Read the above passage and answer the following questions :
(a) Comment on the statement-should production / manufacture of acids be banned?
Give three valid reasons to justify.
(b) As a student of chemistry, what steps would you suggest to combat this social menace?
(c) Recently „Honourable Supreme Court of India‟ has suggested some measures to check such incidents
of acid attack. Comment.
46.
Pooja, a domestic servant of Mrs. Kajol complained of severe pain in the chest while cleaning the utensils.
Mrs. Kajol immediately took her to the nearby hospital where she was diagnosed to be suffering from
Angina Pectoris (angina pain). The doctor prescribed her the medicine commercially called sorbitrate. Mrs.
Kajol also supported her financially to buy the medicine. After reading the above passage, answer the
following questions :
(a) What values are displayed by Mrs. Kajol?
(b) What is the cause of the disease Angina Pectoris?
Page 50
(c) What is sorbitrate made-up of and how is it prepared?
(d) How does sorbitrate work?
(e) Give one more use of the chemical present in sorbitrate.
47.
Why are pentahalides more covalent than trihalides?
48.
How does ammonia react with solution of Cu2+ ions?
49.
What is the covalency of nitrogen in N 2O5?
50.
Why is the bond angle of PH 4 higher than in PH3?
51.
What happens when white phosphorus is heated with NaOH solution in an inert atmosphere of CO 2 gas?
52.
What is the basicity of H3PO4?
53.
What happens when H3PO3 is heated?
54.
Why is H2O a liquid and H2S is a gas?
55.
Complete the following reactions ;
(i)
C2H4 + O2 

(ii) Al + O2 

56.
How is O3 estimated quantitatively?
57.
What happens when SO2 is passed through an aqueous solution of Fe(III) salt?
58.
Comment on the nature of two S  O bonds formed in SO2 molecule. Are these bonds equal in the molecule?
59.
How is the presence of SO 2 detected?
60.
Mention three areas in which H 2SO4 plays an important role.
61.
Why is Ka2 less than Ka1 for H2SO4 in water?
62.
Considering the parameters such as bond dissociation enthalpy, electron gain enthalpy and hydration
energy, compare the oxidising power of F2 and Cl2.
63.
Give two examples to show anomalous behaviour of fluorine.
64.
Sea is the greatest source of halogens. Comment.
65.
Give reason for the bleaching action of chlorine.
66.
Name two poisonous gases which can be prepared from chlorine gas.
67.
Why has it been difficult to study of chemistry of radon?
68.
How is ammonia manufactured industrially?
69.
How is nitrogen prepared in laboratory? Write chemical equations of the reactions involved.
70.
Illustrate how copper metal can give different products on reaction with HNO 3.
71.
The HNH angle value is higher than HPH, HAsH and HSbH angles. Why?
72.
Why does R3P = O exist but R3N = 0 does not (R = alkyl group)?
73.
State the difference in the properties and structures of white and red phosphorus.
Page 51
74.
Knowing the electron gain enthalpy values for O  O and O  O2- as -141 and 702 kJ mol-1 respectively,
how can you account for the formation of a large number of oxides having O 2- species and not O- ?
75.
Describe the contact process for the ' manufacture of sulphuric acid.
76.
Explain why fluorine forms only one oxoacid, HOF.
77.
Why are halogen coloured?
78.
How can you prepare Cl2 from HCl and HC from Cl2? Write reactions only.
79.
Write balanced equations for the following :
(i)
NaCl is heated with sulphuric acid in the presence of MnO 2.
(ii) Chlorine gas is passed into a solution of NaI in water.
80.
Arrange the following in the order of property indicated for each set:
(a) F2, Cl2, Br2, I2 -increasing bond dissociation enthalpy.
(b) HF, HCl, HBr, HI- increasing acid strength.
(c) NH3, PH3, ASH3, SbH3, BiH3 - increasing base strength.
81.
Give the formula and describe the structure of a noble gas-species which is isostructural with:
(a) ICl4
82.
(b) IBr2
(c) BrO3
Why do noble gases have comparatively large atomic size?
Each Question carries 1 Mark
83.
In group 15 elements, there is considerable increase in covalent radius from N to P but small increase from
As to Bi. Give reason.
[Hint : Due to completely filled d- and f-orbital.]
84.
The tendency to exhibit - 3 oxidation state, decreases down the group in group 15 elements. Explain.
[Hint : Due to increase in size electronegativity decreases].
85.
Maximum covalence of Nitrogen is „4‟ but the heavier elements of Group 15 show covalence greater than
„4‟ Why?
86.
Nitrogen exists as a diatomic molecule with a triple bond between the two atoms, whe reas the heavier
elements of the group do not. Assign a reason.
[Hint : P p multiple bonds are formed by N due to its small size.]
87.
The ionization enthalpies of group 15 elements are higher than that of group 14 and 16 elements in the
corresponding period. Assign the reason.
88.
The boiling point of PH3 is lesser than NH3. Why?
89.
NO2 dimerises to form N2O4. Why?
[Hint : Due to presence of odd electron on N]
90.
Draw the structure of N 2O5 molecule.
Page 52
91.
How does ammonia solution react with Ag4- (aq)? Write the balanced chemical equation.
92.
Why does NH3 forms hydrogenbond but PH3 does not?
[Hint : Due to strong electronegativity, small size of Nitrogen atom.]
93.
Give disproportionation reaction of H 3PO3?
94.
How does NH3 acts as a complexing agent?
[Hint : Metal hydroxides dissolved in excess of NH 4OH, Ammonia acts as Lewis base].
95.
Why HF is the weakest acid and HI is strongest acid.
[Hint : Values of dissociation constant.
Ka : (HF) = 7  10-4
(HI) = 7  1011
Intermolecular H-bond in H-F and weak bond in H-I].
96.
Explain Halogens are strong oxidising agent.
[Hint : Ready acceptance of electron.]
97.
Why is Bi(V) a stronger oxidant than Sb(V)?
[Hint : +3 oxidation state is more stable than +5 ox. state in Bi].
98.
Why SF4 is easily hydrolysed, whereas SF6 is not easily hydrolysed?
[Hint : Water molecule can not attack due to steric hinderance in case of SF 6 molecule.]
99.
Bond dissociation energy of F2 is less than that of Cl2. Why?
100.
Write the reaction of PCl5 with heavy water.
[Hint : PCl5 + D2O  POCl3 + 2DCl]
101.
How many P  O  P bonds are there in cyclotrimetaphosphoric acid?
[Hint : 3 bonds]
102.
In group 16, the stability of +6 oxidations state decreases and that of +4 oxidation state increases down the
group. Why?
[Hint : Inert pair effect]
103.
Why we can not prepare HBr by heating KBr with sulphuric acid.
[Hint : As HBr is reducing agent and H2SO4 is oxidising agent.]
104.
Explain sulphur disappears when boiled with aqueous solution of sodium sulphite.
[Hint : Sulphur combines with Na 2SO3, forming soluble sodium thiosulphate.]
105.
Write the equation for the decomposition of hydrogen peroxide in the presence of finely divided metal and
MnO2 as catalyst.
106.
Fluorine exhibit only -1 oxidation state whereas other halogens exhibit +ve oxidation states also. Explain.
107.
Arrange the following oxoacids of chlorine in increasing order of acidic strength.
HOCl, HOClO, HClO3, HOClO3
Page 53
108.
The majority of known noble gas compounds are those of Xenon. Why?
109.
“Hypophosphorus acid is a good reducing agent.” Justify with an example.
[Hint : 4AgNO3 + H3PO2 + 2H2O  4Ag + HNO3 + H3PO4.
110.
Draw the structure of H4P 2O7 and find out its basicity?
[Hint : Tetrabasic]
111.
Arrange the following triatomic species in the order of increasing bond angle. NO2 , NO2 , NO2
[Hint :
NO2 has one non-bonding electron, NO2  has 2 non-bonding e-, NO2+ has no non-bonding e- on N atom.

Bond angle of NO2 is maximum but NO2  is minimum].
112.
With what neutral molecule ClO - is isoelectronic.
113.
Draw the structure of H 2S2O8 and find the number of S  S bond if any.
114.
What is cause of bleaching nature of Chlorine water? Explain it with chemical equation?
[Hint : Evolution of Nascent Oxygen]
115.
The negative value of electron gain enthalpy of fluorine is less than that of chlorine.
[Hint. : Due to small size of F atom, there are strong inter electronic repulsions in the relatively smaller 2p
orbitals of fluorine. So the incoming electron does not experience attraction.]
116.
Which one of the following is not oxidised by O 3. State the reason. Kl. FeSO4, K2MnO4, KMnO4
[Hint. : KMnO4 since Mn is showing maximum oxidation state of +7.]
117.
Complete the reaction Ca 3P 2 + H2O 

Each Question carries 2 Marks
118.
PCl5 is known but Pl5 is not known Why?
[Hint: 5 Cl atom can be accommodated around P atom, I being larger cannot be accommodated.]
119.
Why is red phosphorous denser and less chemically reactive than white phosphorous.
120.
Give chemical reaction in support of the statement that all the bonds in PCl5 molecule are not equivalent.
121.
Account for the following :
(a) XeF2 has a straight line structure and not a bent angular structure.
(b) Phosphorous show marked tendency of Catenation.
122.
Draw the structure of BrF3, XeOF4, XeO3, N2O3.
123.
Write the conditions that favour the formation of ammonia gas along with the reactions involved in Haber‟s
Process.
Page 54
124.
Write the chemical equations of the following reactions
(a) Glucose in heated with cone. H 2SO4.
(b) Sodium Nitrate is heated with cone. H 2SO4.
Complete the following reactions :
125.
(i)
(NH4)2 Cr2O7 

(ii) NH4Cl (aq) + NaNO2 (aq) 

126.
(i)
NH2CONH2 + H2O 

(ii) FeCl3 (aq) + NH4OH 

127.
(i)
Ca3P 2 + H2O (l) 

(ii) I2 + HNO3 (conc.) 

128.
(i)
Ba(N3)2 

(ii) 4H3PO3 


129.
(i)
PH4I + KOH 

(ii) HgCl2 + PH3 

130.
(i)
PCl3 + 3H2O 

(ii) S + H2SO4 (conc.) 

131.
(i)
Al2O3(s) + NaOH (aq) + H2O(l) 

CuCl2

(ii) HCl + O2 
132.
(i)

Ca(OH)2 + Cl2 

(ii) XeF4 + H2O 
133.
(i)

Na2SO3 + Cl2 + H2O 

(ii) NaHCO3 + HCl 
134.
(i)
Complete

XeF6 + H2O 
Hydrolysis
Partial

(ii) XeF6 + H2O 
Hydrolysis
135.
(i)
What is the covalency of N in N 2O3?
(ii) Explain why phosphorus forms pentahalide whereas nitrogen and bismuth do not?
136.
(i)
The acidic character increases from H 2O to H2Te. Why?
(ii) Dioxygen is a gas while sulphur (S8) is a solid. Why?
137.
(i)
Interhalogen compounds are more reactive than halogens. Why?
(ii) Give one important use of ClF3.
Page 55
138.
(i)
Write the composition of bleaching powder.
(ii) What happens when NaCl is heated with cone. H 2SO4 in the presence of MnO2.
Write the chemical equation.
139.
Arrange the following in the decreasing order of their basicity. Assign the reason :
PH3, NH3, SbH3, AsH3, BiH3.
140.
A colourless and a pungent smelling gas which easily liquifies to a colourless liquid and freezes to a white
crystalline solid gives dense white fumes with ammonia. Identify the gas and write the chemical equation
for its laboratory preparation.
[Hint : HCl]
141.
Why are the following reactions regarded as disproportionation reactions?
(a) P 4 + NaOH + H2O 


H

(b) HNO2 
142.
Suggest reason why only known binary compounds of noble gases are fluorides and oxides of Krypton,
Xenon and Radon.
[Hint : F and O are most electronegative elements]
143.
Which fluorinating agent are often used instead of F2? Write two chemical equations showing their use as
fluorinating agents.
[Hint :
BrF5 + 3H2O 
 HBrO3 + 5HF
2IF7 + SiO2 
 2IOF5 + SiF4]
144.
(a) Hydrolysis of XeF6 is not regarded as a redox reaction. Why?
(b) Write a chemical equation to represent the oxidising nature of XeF4.
[Hint : (ii) XeF4 + 2H2 
 Xe + 4HF)]
145.
Write Chemical equation :
(a) Cl2 reacts with hot cone, solution of NaOH.
(b) PtF6 and Xenon are mixed together.
Each Question carries 3 Marks
146.
(i)
How is HNO3 prepared commercially. Name the process.
(ii) Write chemical equations of the reactions involved.
(iii) What concentration by mass of HNO 3 is obtained.
147.
(i)
How does O3 react with Lead sulphide, Write Chemical equation.
(ii) What happens when SO2 is passed in acidified KMnO 4 solution.
(iii) Explain : behaviour of SO2 is similar to CO2.
Page 56
148.
Assign reason for the following :
(i)
Sulphur in vapour state exhibits paramagnetism.
(ii) F2 is strongest oxidising agent among halogens.
(iii) Inspite of same electronegativity oxygen forms hydrogen bond while chlorine does not.
149.
Give appropriate reason for each of the following :
(i)
Metal fluorides are more ionic than metal chlorides.
(ii) Perchloric acid is stronger than Sulphuric acid.
(iv) Addition of chlorine to Kl solution gives it a brown colour but excess of Cl2 makes it colourless.
Hint :
(i)
According to Fajan‟s Rule bigger ions more polarised than the smaller ion by a particular cation.
(ii) Oxidation state of Cl in HClO 4 is +7 white oxidation state of S in H 2SO4 is +6, Hence OH bond easily
breaks in the HClO4 molecule.
2Kl + Cl2 
 2KCl + I2
(iii)
Excess 5Cl2 + I2 + 6H2O 
 2HlO3 + 10 HCl Colourless.
150.
Explain that :
(i)
No chemical compound of Helium is knwon.
(ii) Bond dissociation energy of fluorine is less than that of chlorine.
(iii) Two S  O bonds in SO2 are identical.
151.
(i)
How O2 can be converted to O3
(ii) How Cl2 is manufactured by Deacon‟s process.
(iii) How Cl2 reacts with hot and cone. NaOH.
152.
Out of the following hydrides of Group 16 elements which will have :
(i) H2S
(ii) H2O
(iii) H2Te
(a) Lowest boiling point
(b) highest bond angle
(c) highest electropositive hydroden.
153.
(i)
How is XeO3 prepared from XeF6. Write the chemical equation for the reaction.
(ii) Draw the structure of XeF2, XeF4.
154.
(i)
Thermal stability of hydrides of group 16 elements decreases down the group. Why?
(ii) Compare the oxidising powers of F2 and Cl2 on the basis of bond dissociation enthalpy.
(iii) Write the chemical equation for the reaction of copper metal with cone. HNO 3.
Page 57
155.
An unknown salt X reacts with hot cone. H 2SO4 to produce a brown coloured gas which intensifies on
addition on copper turnings. On adding dilute ferrous sulphate solution to an aqueous solution of X and
then carefully adding cone. H 2SO4 along the sides of the test tube, a brown complex Y is formed at the
interface between the solution and H2SO4 . Identify X and Y and write the chemical equation involved in
the reaction.
[Hint : X is NO 3 salt].
156.
Assign reason for the following :
(i)
Noble gases have large positive value of electron gain enthalpy.
(ii) Helium has the lowest boiling point than any known substance.
157.
Arrange the following in the order of the property indicated for each set (a) F2, Cl2, Br2, I2- (Increasing bond dissociation energy).
(b) HF, HCl, HBr, HI (Increasing acid strength).
(c) NH3, PH3, ASH3, SbH3, BiH3 (Increasing base strength).
Hint :
(a) F2 has exceptionally small bond dissociation enthalpy. F atom is very small, three lone pair of electrons
repel the bond pair holding the F atoms in F2 molecule.
(b) Depends upon H  X bond dissociation enthalpy as the size of atom increases, acid strength also
increases from HF  HI.
(c) Lonepair of electrons occupies a large volume in bigger atoms. As a result basicity decreases.
158.
A transluscent while waxy solid (A) on heating in an inert atmosphere is converted to its allotropic form
(B), Allotrope (A) on reaction with very dilute aqueous NaOH/KOH liberates a highly poisonous gas (C)
having a rotten fish smell, with excess of chlorine forms D which hydrolyses to form compound (E)
identify the compounds (A) to (E).
159.
Write balanced equation for the following reactions :
(a) Zn is treated with dilute HNO 3.
(b) NaCl is heated with H 2SO4 in the presence of MnO2.
(c) Iodine is treated with cone. HNO 3.
160.
X2 is a greenish yellow gas with pungent offensive smell used in purification of water. It partially dissolves
in H2O to give a solution which turns blue letmus red, When X2 is passed through NaBr Solution, Br2 is
obtained.
(a) Identify X2, Name the group to which it belongs.
(b) What are the products obtained when X2 reacts with H2O? Write chemical equation.
(c) What happens when X2 reacts with cone. NaOH. Give equation.
Page 58
161.
Assign the appropriate reason for the following:
(a) Nitrogen exist as diatonic molecule and phorphorous as P 4, Why?
(b) Why does R3P = 0, exist but R3N = 0 does not (R = alkyl group).
(c) Explain why fluorine forms only one oxoacid, HOF?
Hint :
(a) Due to its small size and high electronegativity N forms P  P multiple bond (N  N). whereas P
does not form P  P bonds instead forms P - P single bond.
(b) Due to absence of d-orbital, N cannot expand its covalence beyond four.
In R3N = 0, N should have a covalence 5 so the compound R 3N = 0 does not exist.
(c) Due to high electronegativity and small size, F does not form oxoacids in which the oxidation state of
F would be +3, +5, +7, it forms one oxoacid having +1 oxidation state of F.
Each Question carries 5 Marks
162.
How is PH3 prepared in the laboratory? How is it purified? How does the solution of PH 3 in water react on
irradiation with light and on absorption in CuSO 4? How can you prove that PH3 is basic in nature?
Write the chemical equations for all the reactions involved.
163.
Assign a possible reason for the following :
(a) Stability of +5 oxidation state decreases and that of +3 oxidation state increases down the group 15
elements.
(b) H2O is less acidic than H 2S.
(c) SF6 is inert while SF4 is highly reactive.
(d) H3PO2 and H3PO3 act as good reducing agents while H 3PO4 does not.
(e) Noble gases have comparatively large size in their respective period.
164.
(a) How is XeF6 prepared from the XeF4? Write the chemical equation for the reaction.
(b) Deduce the structure of XeF6 from VSEPR theory.
(c) How does XeF2 reacts with PF5?
(d) Give one use each of helium and Neon.
(e) Write the chemical equation for the hydrolysis of XeF4.
165.
(a) Why does nitrogen show anomalous behaviour? Discuss the trend of chemical reactivity of group 15
elements with.
(a) Oxygen
(b) 'Halogens
(c) Metals
(b) H3PO2 is a dibasic acid. Why?
Page 59
166.
(a) Arrange the following in the order of their increasing acid strength.
(b) Cl2O7, SO2, P 4O10
(c) How in N2O gas prepared.
(d) Give one chemical reaction to show O 3 is an oxidising agent.
167.
Identify A, B, C, D and E in the following sequence of reactions
Complete the reactions of the above mentioned sequence.
[Hint : A is P 4].
168.
A white waxy, translucent solid, M, insoluble in water but soluble in CS 2, glows in dark. M dissolves in
NaOH in an inert atmosphere giving a poisonous gas (N). Also M catches fire to give dense white fumes of O:
(a) Identify M, N and O and write the chemical equations of the reactions involved.
(b) M exist in the form of discrete tetrahedral molecule. Draw its structure.
(c) M on heating at 573 K is changed into other less reactive form, Q, which is non-poisonous, insoluble in
water as well as in CS2 and does not glow in dark, Identify Q and draw its structure.
169.
Write the structure of A, B, C, D and E in the following sequence of reactions :
Pt/Rh
 A + H2O
NH3 + O2 
A  O2 
 B (Brown fumes)
B  H2O 
 C + A (C is an oxoacid)
C  I 
 D (Violet vapours)
Complete reactions of the above mentioned sequence and name the process.
[Hint. : A is NO].
170.
Give reason for each of the following :
(a) Molten alumina is a poor conductor of electricity.
(b) Ammonia is a good complexing agent.
(c) Bleaching by SO2 is temporary.
(d) PCl5 is ionic in solid state.
(e) Sulphur in vapour form exhibits paramagnetism.
Page 60
171.
Knowing the electrons gain enthalpy value for O  O- and O-  O2- as -141 and 720 kJ mol-1 respectively,
how can you account for the formation of large number of oxides having O2 species and not O-?
[Hint: Consider lattice energy factor in the formation of compound. The reaction of divalent metal (M)
with oxygen to form M2O and MO involves following reaction steps.
i H1
i H2
M(g), 
M (g) 
 M2 (g)
 H
 H
eg 1
eg 2
O(g) 
 O (g) 
 O2 (g)
Lattice Energy
2M+ (g) + O (g) 
 M2O (s)
Lattice Energy
M2 (g)  O2 (g) 
 MO (s)
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