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Roll No.
Series 08789
Code No. 043
Navodaya Vidyalaya Samiti
Chemistry (Theory) Sample Paper - 2
th
Class-12
Time allowed: 3 Hours
Maximum Marks: 70
General Instructions:
(i)
All questions are compulsory.
(ii)
Marks for each question are indicated against it.
(iii)
Questions number 1 to 8 are very short answer questions and carry 1 marks each.
(iv)
Questions number 9 to 18 are short answer questions and carry 2 marks each.
(v)
Questions number 19 to 27 are also short answer questions and carry 3 marks each.
(vi)
Questions number 28 to 30 are long answer questions and carry 5 marks each.
(vii)
Use Log Tables, if necessary. Use of calculators is not allowed.
Q1
Give the IUPAC name of the following.
1
CH3
COOH
Q2
Write the balanced equation, when Nacl is heated with sulphuric acid in the
1
presence of MnO2
Q3
Why does physical adsorption decreases with the increase of temperature?
1
Q4
Write the structure of 3 Cyclo hexyl Pentan-3-ol.
1
Q5
How many effective sodium ions are located at the centres of faces of a unit cell in
1
a sodium chloride crystal?
Q6
Define Vant’ Hoff factor. What is its value for a non-electrolytic solution?
1
Q7
Out of C and CO, which is better reducing agent for ZnO?
1
Q8
With what neutral molecule is ClO- iso electronic? Is that molecule is lewis base?
1
Q9
How will you determine the molecular mass of a substance from osmotic
2
pressure?
Q10
Show that the time required for 99% completion of a first order reaction is twice
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2
the time required for the completion of 90%.
Q11
Al2O3 + 2Cr ( ∆Go=-421 KJ) is
The reaction Cr2O3 + 2Al
2
thermodynamically feasible as is apparent from the Gibbs energy value. Why does
it not take place at room temperature?
Q12
Define the following related to proteins.
(a) Peptide Bond
Q13
2
(b) Denaturation
What are essential and non-essential amino acids? Give two examples of each
2
type.
Q14
Write the mechanism of hydration of ethene to form ethanol.
2
Q15
Write the following name reaction
2
(a) Aldol Condensation
Q16
(b) Clemensons Reduction
Give one chemical test each to distinguish between following pairs of compound.
2
(1) Aniline and Benzylamine
(2) Ethanal and Propanal
Q17
Give reasons for the following
2
(1) Cyclohexanone forms cyanohydrin in good yield but 2,2,,6 -trimethyl cyclo
hexanone does not.
(2) Why are aliphatic amines stronger bases than aromatic amines?
OR
(1) Why cannot aromatic primary amines be prepared by Gabriel Phthalimide
synthesis?
(2) There are two –NH2 groups in semi carbazide. However only one is involved
in the formation of semi carbazones.
Q18
Calculate the mass of a non-volatile solute (molar mass 40 gm mole-1), which
2
should be dissolved in 114 gm octane to reduce its vapour pressure to 80%.
Q19
The density of KBr is 2.75 gm cm-3. The length of edge of the unit cell is 654 pm.
3
Predict the type of cubic lattice to which unit cell of KBr belongs.
(No= 6.023x1023mole-1, At. Mass K=39, Br=80)
Q20
How are polymers classified on the basis of forces operating between their
3
molecules? To which of these classes does nylon –6, 6 belong?
Q21
With the help of valence bond theory, compose the magnetic behavior of
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[Co(NH3)6]+3 and [CoF6]-3 complexions.
Q22
Briefly explain the following terms.
3
(a) Hardy- schulze rule
(b) Electro phoresis
(c) Coagulation
Q23
(a) Complete the following reaction.
3
BrO3- + F2 + OH(b) SF6 is known but SH6 is not known. Explain.
(c) PCl5 exists as [PCl6]- [PCl4}+ but PBr5 exists as [PBr4]+ [Br]-. Explain.
Q24
Q25
The rate constant for the first order decomposition of H2O2 is given by the
following equation
LogK= 14.34 – 1.25 x 104 K/T
Calculate Ea for this reaction and at what temperature will its halt life-period be
256 minutes?
(a) Which of the following has the highest dipole moment?
(i) CH2Cl2 (ii) CHCl3 (iii) CCl4
(b) Why haloarenes are less reactive than halo alkanes..
3
3
(c) In the following pair of halogen compounds which would undergo SN2
reaction faster and why?
(a)
Q26
CH2Cl &
Cl
(b)
I &
Cl
Give reasons
3
(a) Bond angle in PH4+ is higher than that in PH3. why?
(b) Why does R3P=o exist but R3N=o does not (R=alkyl group)?
(c) Why does NH3 form hydrogen bond but PH3 does not?
OR
(a) Describe the manufacture of H2So4 by contact process?
(b) Why are halogens coloured?
Q27
(a) How do antiseptic differ from disinfectants? Give one example of each.
(b) What is meant by the term Broad Spectrum Antibiotics? Give its one example.
(c) How soaps differ from detergents?
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Q28
Q29
Q30
An organic compound (A) (molecular formula C8H16O2) was hydrolysed with
dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C). Oxidation
of (C) with chromic acid produce B. (C) on dehydration gives but –1-ene. Write
equations for the reactions involved.
OR
An aromatic compound ‘A’ on treatment with aqueous ammonia and heating
forms compound ‘B’ which on heating with Br2 and KOH form a compound C of
molecular formula C6H7N. Write the structures and IUPAC name of compound A,
B and C.
(a) What are fuel cells? Give two advantage of fuel cell over ordinary cells.
(b) Write the Nernst equation and calculate the e. m. f. of the following cell at
298K
Sn+2(0.050M) || H+ (0.020M)| H2(g) (1bar) | Pt(S)
E0 Sn+2/Sn = 0.14 V
(c) Define specific conductance.
OR
(a) Define corrosion. Describe electro chemical reaction of rusting of iron.
(b) Calculate the e. m. f. of the cell Zn (S) | Zn+2 (0.1M) || Cd+2 (0.01M) | Cd(S)
at 298K.
Given E0 Zn+2/Zn = -0.76V, E0 Cd+2/Cd = -0.40V
(c) How molar conductivities of strong and weak electrolyte varies with
concentration?
Give reason.
(a) Transition metals are well known to form interstitial compounds, why?
(b) Zn+2 salts are white Cu+2 salts are blue. Why?
(c) Mn(II) shows maximum paramagnetic character amongst divalent ions of first
transition series why?
(d) Why do actinoids, in general exhibit a greater range of oxidation states than
lanthanoids.
(e) Transition metal ions are usually coloured.
OR
(a) The chemistry of actinoids elements is not so smooth as that of the lanthanoids.
Justify this statement by giving some examples from the oxidation state of these
elements.
(b) K2 [PtCl6] is a well-known compound where as the corresponding Ni
compound is not known. State reason for it.
(c) Why is La (OH)3 stronger base than Lu(OH)3?
(d) What are misch metals? Give one example.
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