Download Solved Guess Paper – 3 Q1. Define the term molarity . Ans

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Solved Guess Paper – 3
Q1. Define the term molarity .
Ans- Molarity is defined as the number of moles of the solute per kilogram of
the solvent .
Q2. What is the Van’t Haff factor for potassium sulphate in very dilute
aqeow solution .
Ans- Tha van’t haff factor for potassium is 3 .
Q3. Mention the concentration of H+ ions in the solution used in SHE .
Ans- 1M or 1 molar concentration of H+ ions in the solution used in SHE .
Q4. The unit of rate constant of a reaction is mol-1Ls-1 . What is the order of
the reaction .
Ans- Second order reaction since the unit of rate constant is mol-1Ls-1 .
Q5. Among Al2(SO4)3 and (NH4)3PO4 which is better coagulating agent for
a negative sol.
Ans- Al2(SO4)3 is the coagulating agent for the negatine sol because Al3+ is
more effective than NH4+ .
Q6- Name the reducing agent used in the extraction of Zinc from zinc oxide
Ans- Coke (carbon) is the reducing agent used in the extraction of zinc from
zinc oxide .
7. Name the main commercial source of helium ?
Ans- Natural gas is the main source of helium .
8. R  X  NaI  R  I  NaX. The reaction is known as .......
Ans- Finkelsten reaction .
9. Give reasons ; hydrogen atoms of aldehyde and ketones are acidic ?
Ans- Hydrogen atoms of aldehyde and ketons are acidic due to the strong
electron withdracing effect of the carbonyle group and reasonance stabilisation
of conjugate base .
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10. What are non- essential amino acids ?
Ans- The amino acids which can be synthesised in the body are known as nonessential amino acids .
PART – B
11 a. Mention one consequence of metal excess defect .
b. Give an example for molecular solid .
Ans- a. Metal excess defect is due to anionic vacancies and extra contains at
interstitial site . The anionic sites are occupied by unpaired electrons are called
F- centres which imparts colour to the crystal .
b. H2, Cl2 , solid SO2 , Solid NH3 etc are the example for molecular solid .
12. Write the symbolic representation of standard hydrogen electrode
(SHE) and give its standard potential value .
Ans- The symbolic representation of standard hydrogen electrode is Pt(s)/H 2 (g,
l bar) | H+ (aq. 1M)
The standard electrode potential of SHE is OV .
13. Drive the example for half- life of zero order reaction .
Ans- Half- life of zero- order reaction .
The integral rate equation for zero order reaction is [R]  kt  [R]0 ....(1)
If t  t1/ 2 , [R] 
[R]0
2
Substituting in eqn. (1)
[R]0
 kt1/ 2  [R]0
2
kt1/ 2  [R]0 
kt1/ 2 
[R]0
2
2[R]0  [R]0
2
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kt1/ 2 
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[R]0
2k
[R]0 

 t1/ 2  2k 


Half- life period of zero order reaction is directly proportional to initial
concentration .
14. Give an example for heteroleptic complex .
Ans- when more than one type of ligands are present , then the complex is
called as hetroleptic complex .
Ex :[Pt(NH3 )2 Cl 2 ];[CO(NH3 )4 Cl(NO2 )] ,[CoCl 2 (CN)2 ] etc.
15. A carbonyl compound (p) with the formula C2H4O reacts with
CH3MgX followed by hydrolysis to form an alcohol (Q). Name the alcohol .
Write the chemical equation of the reaction .
Ans- The product obtained is proponol .
H

 H O/ H 
|
2
CH 3  C  O  CH 3MgX  CH 3  C_ OMgX  
 CH 3  CH 2  CH 2  OH 


CH 3
H
|
X
Mg  OH
16. write the chemical equation for the reaction b/w dilute NaOH and
acetaldehyde , mention in the name of the product formed .
Ans – The chemical equation is :
β
α
dil.NaOH


2CH 3CHO 
CH 3  CH
 CH 2  CHO 
 CH 3  CH  CH  CHO
H 2O
|
OH
17. What are food preservatives ? Give one example .
Ans- Food preservations ; The substances that is added to food to prevent
spilage due to microbial growth .
Ex.- Sodium chloride , Sodium benzoate
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18. What are artificial are the chemicals that sweeten food and does not
add colories to our body .
Ex – Saccharin , Sucrolose , Alitame
PART – C
19. On the basis of Ellingham’s diagram explain the principle of extraction
iron from its iron oxide .
Ans- Extraction of iron from iron oxide are
The reduction of iron oxide to iron is explained using ellingham’s diagram . The
reduction of Fe2O3 to F2O taking place and in the other , e is being oxidized to
CO .
1
FeO(s)  Fe(s)  O2 (g)  G (feO,fe) 
2
1
C(s)  O2 (s)  CO  G[C3CO) 
2
When both the reaction takes place to yield the net libbs free energy change
becomes
G(C,CO)  G(feo,fe)  rG
The reactions takes places when the above reaction is negative . In G 0 is T plot
representing reactions . If the plot goes upward which represents the change
C  CO (C,CO) goes downward . At temperature above 1073k the C, Co line
comes below fe, feo line so in this range coke will be reducing the FeO and will
itself oxide to CO .
FeO  C  Fe  CO
20 . Draw the flow chart for the manufacture of sulphuric acid by contact
process .
Give one example of interhalogen compounds .
Ans- Flow chart for the manufacturing of sulphuric acid .
 Dust

 Tyndall 
SO2  O2

  Drier   
S  O2  


chamber 
box

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 Fu min g 
catalytic  SO3 absorption 
SO2

chamber   chamber    H S O 




 2 2 7 
b). Example for interhalogen compounds are ClF, ClF3 , Icl , etc.
21. How does phosphorous reacts with limited amount of chlorine ? Give
equation .
Write the structure of sulphurous acid .
Ans- Phosphorous reacts with limited amount of chlorine to form phosphorous
trichloride .
2P4  12cl 2  8Pcl 3
Structure of sulphurous acid [H2SO3]
HO  S|  O
OH
22. Complete the reaction .
(a). SO3  conc.H2SO4  ?
Mno
?
(b). 2KclO3 
2
?
?
(c). Zn  dilute HNO3 
Sol.- (a). SO3  conc.H2SO4  H2S2O7
MnO
 2Kcl  3O2
(b). 2KclO3 
2
(c). Zn  dilute HNO3  Zn(NO3 )2  3O2
23. write ionic equation for the reaction of dichromate ions with
i). Hydroxide ions
ii). Fe 2+ ions in acidic medium . In which one of the
above two reactions will the oxidation number of chromium remains unchanged
?
Ans- K 2Cr2O7  2KOH  2K 2Cr2O4  H2O
(ii). K 2Cr2O7  7H2SO4  6FeSO4  K 2SO4  Cr2 (SO4 )3  3Fe2 (SO4 )3  7H2O
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In the reaction of dichromate ions with hydroxyl the O, N of chromium remains
unchanged .
24. Give reasons
(a). Most of the transition metals have high melting point and boiling point .
b). 2nd ionization enthalpy of Cu is exceptionally high .
25(a). Calculate the packing efficiency in a Fcc/HCP/CCP
(b). What is ferromagnetism ? Give an example for ferromagnetic
substance .
Ans (a). Packing efficiency of FCC
Edge length = a
Face diagonal = b
In ABC
AC2  AB 2  BC2
b2  a2  a2
b 2  2a 2
b  2a
In ‘r’ is the radius of the sphere
b  4r  2a
a  2 2r
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Volume of the sphere , v  a5  (2 2r)5
Packing efficiency of FCC 
volumeoccupiedby 4sphere
 100
total volumeof thesphere
4
4  πr 3
3

 100
(2 2π)3
= 74%
(b). Ferromagnetism are strongly attracted by the magnetic field . They acts as
permanent magnets .
Ex: Iron, Cobalt , nickel
26(a). A 4% solution of a non – volatile solute is isotonic with 0.72% urea
solution . Calculate the molar mass of the non- volatile solute . (Molar mass
of urea = bog mol-1)
(b). Plot a graph of vapour pressure against mole fraction of the two
volatile liquids forming an ideal solution / non- ideal solution with +ve
derivation / non ideal solution with negative derivation .
(a). For isotonic solution
w1 w 2

M1 M 2
Where w1 = 0.702g , w2 = 4g, M1 = 60
 M2 
M2 
w 2 M1
w1
40  60
 341.8g mol 1
7.02
(b). Volutile liquids formingideal solution .
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Position deviation :
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Negative deviation :
27 a. Write the reaction taking place at anode and cathode during
corrosion of iron .
b. Write the anodic and cathodic half –cell reactions taking place in Daniel
cell .
Ans- a). Corrosion of iron .
At cathode
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2Fe  2Fe2  4e
It occurs in the presence of water and air at a particular spot of iron called anode
.
At cathode :
O2  4H  4e  2H2O
Electron moves from anodic spot through the metal and goto the another spot on
the metal and reduce oxygen in the presence of H+ . This spot behaves as
cathode .
b). Half cell reaction
At anode
Zn(s)  Zn2 (aq)  2e
At cathode
cu2  2e  cu
28 a. Show that for first order reaction t87.5% = t30%
b). The rate of a reaction increases by 4 times when the temperature of the
reaction is raised from 340k to 360k . Calculate the energy of activation of the
reaction . Given R = 8.314 J/k/mol
Ans- (a). Expression for k when 87.5% of reactant is reacted .
k
2.303
100
log
t 87.5%
12.5
k
2.303
log 8
t 87.5%
k
2.303
 0.9031 ....(1)
t 87.5
k
[R]0
2.303
log
t
[R]
[R]0  100
[R] = 100 – 87.5 = 12.5
Expression for k when 50% of reactant is reacted .
[R]0 = 100 , t = t50%
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[R] = 100 – 50 = 50
k
2.303
100
log
t 50%
50
k
2.303
log 2
t 50%
k
2.303
 0.3010 ....(2)
t 50%
Divides eqn. (1) by (2)
2.303
 0.9031
t 87.5%
2.303
k
 0.3010
t 50%
k
t
t 50% 0.9031

t 87.3% 0.3010
t 87.5%  t 50% 3
t 87.5%  3t 50%
(b). Given
T1 = 340k , Ea = ?
T2 = 360k
K=4
log
Ea  T2  T1 
k1



k 2 2.303R  T1T2 
log 4 
Ea
 360  340 
2.303  8.314  360  340 
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Ea
 360  340 
 log 4
2.303  8.314  360  340 
Ea
 20 
 0.6021
19.147142  122400 
0.0001634
Ea 
 0.6021
19.147142
0.6021  19.147142
0.0001634
11.5285
Ea 
0.0001634
Ea  70554J (or) 70.554KJ
Ea 
29(a). What are the effect of the electron with drawing and electron
donating groups on acidity of carboxylic acid .
b. How does ketone react with ethylene alchole . Write chemical equation
for the reaction .
Ans- (a). Effect of electron with drawing group on carboxylic acid .
Electron withdrawing group increases acidity of carboxylic acid by conjugate
base through resonance or inductive effect .
Ex: ClEffect of electron donating group on carboxylic acid electron donating group
decrease the acidity of conjugate base .
Ex.- CH3 is electron donating group .
30 a. Explain Halff mann bromamide reaction with .
b). Ketones reacts with ethylene glycol in the presence of HCl to form ethylene
glycol ketal .
R
R
R   O  CH
C  O  CH 2OH 
 R  C OCH22  H 2O
HCl
|
CH2OH
31a. Explain Hoffmann bromamide reaction with an example .
b. Carbyl amine reaction by taking methyl amine as an example .
c. Explain helium reduction with an equation .
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Ans- a. When an amide is heated with a mixture of bromine and sodium
hydroxide , primary amines are formed . This reaction is called as Hoffmann
degradation or Hoffmann bromomide reaction .
O
||
Ex :  CH 3  C NH 2  Br2  4NaOH  H 3C  NH 2  Na 2CO3  2NaBr  2H 2O
b). Carbylamine reaction :
when methyl amine is heated with chloroform and alcoholic potassium
hydroxide solution . It gives methyl isocyanide .
alcoholic

 CH3  NC  3KCl  H2O
Ex:- CH3NH2  CHCl 2  3KOH 

c). Mendior reaction [Reduction of nitride]
The reaction of nitrile using Na in Hg in ethanol gives primary amine called
Mendeur’s reaction .
NainHg/C H OH
 R  CH2  NH2
Ex.- RCN 
2
5
NainHg/C2 H5OH
CH3  CN 
 CH3  CH2  NH2
32. What is (i). Tyndall effect (ii). Peptisation
(b). Mention two factors which effects adsorption of a gas on a solid .
(c). What do you mean by selectivity of a catalyst .
Ans- (a). i. The phenomenon of scattering of light by the colloidal particles is
called as tyndall effect .
33. Factor affecting absorption of a gas on a sold .
Nature of a gas (adsorbate)
Nature of the solid (adsorbate)
Pressure of the gas
Surface area of the solid
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(c). The ability of catalyst to direct the reaction to produce a particular product
in greater yield is called selectivity .
34.a. What is Zuter ion of an amino acid ? Give its general formula
b. What are difference b/w DNA and RNA
c. Mention the diffenciency of vitamin c
Sol.- a. In solution the carbonyl group can be loose a proton and amino group
can accept a proton giving rise to the dipolar ion known as Zwitter ion .
(b).
DNA
RNA
1, DNA has double strand helix (i). RNA has a single strand helix
structure .
structure .
(ii). DNA is responsible for identity of (ii). RNA is responsible for the
different species , chemical base for synthesis of protein in cell .
heredity .
(iii). DNA is composed of B-D-2 (iii). RNA is composed B-D- ribosugar
dexoyribosugar phosphoric acid and , phosphoric and nitrogen containing
nitrogen
containing
heterocyclic hetrocyclic component .
component .
c. Deficiency of vitamin c leads to survey (bleeding gums).
37. a. What is vulcanization of rubber .
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b. How is Buna – N prepared. Write its equation .
c. Give the lUPAC name of the monomer of natural rubber .
Ans- Vuleanization of rubber means heating a mixture of raw rubber with
sulphuric acid at a temperature tange b/w 373k – 415k . Thus the rubber gets
solvent soft to the stiffin [hand].
b. Buna –N is obtained by w-polymerisation of 1,3 buta –dine airylonite in the
presence of periodic catalyst .
c. The iUPAC name of isoprene is .
2- methyl -1, 3 –Buta diene .
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