chemistry in daily life

II PUC – CHEMISTRY (34)
MODEL QUESTION PAPER - 1
Time: 3hours 15 minutes

Maximum marks: 70

Instructions:
1. The question paper has four parts: A, B, C and D. All parts are compulsory.
2. Write balanced chemical equations and draw labeled diagrams wherever required.
3. Use log tables and the simple calculator if necessary.
(Use of scientific calculators is not allowed)
PART-A
I. Answer ALL of the following. (Each question carries 1 mark)
10x1=10
(Answer each question in one word or in one sentence)
1. Name a colligative property.
2. What does the Van’t Hoff factor ‘ i ’ for a solute in a solvent account for?
3. What is a secondary cell?
4. By how many times does the t½ of zero order reaction increase if the initial concentration of the reactant is doubled?
5. Name the catalyst that catalyzes the decomposition of KClO3 into KCl and O2.
6. Give the composition of ‘copper matte’.
7. What is the structure of XeF2?
8. A racemic mixture is optically inactive. Why?
9.
10.

+ X. Give the IUPAC name of X.

What does the primary structure specify about the structure of a protein.
PART-B
II. Answer any FIVE of the following. (each question carries 2 marks)
5x2=10
11. Give two differences between Schottky and Frenkel defects in ionic solids.
12. Name the gases liberated at anode and cathode respectively when an aqueous solution of sodium chloride is electrolysed.
13. Given 2NO(g) + O2 (g) ¾¾ 2NO2(g) ; rate = k[NO]2 [O2]1. By how many times
®
does the rate of the reaction change when the volume of the reaction vessel is reduced to 1/3rd of its original volume? Will there be any change in the order of the reaction?
14. Give reasons: i) actinoids show variable oxidation states ii) Zr and Hf have almost identical radii
15. What is Lucas reagent? Between primary and tertiary alcohols, which one of these will react faster with Lucas reagent?
16. A carboxylic acid is treated with alcohol in presence of conc. H2SO4. Name the reaction. Give its general equation.
17. What are food preservatives? Give an example.
18. Name any two types of synthetic detergents.

PART-C
III. Answer any FIVE of the following. (each question carries 3 marks) 5x3=15
19. Describe the three steps involved in the leaching of bauxite to get pure alumina
(equations not expected).
3
20. White phosphorus is heated with excess of dry chlorine to get X. X on hydrolysis finally forms an oxyacid of phosphorous Y. What are X and Y? What is the basicity of acid Y?
3
21. Describe the preparation of ozonised oxygen with an equation. Name the oxidized product obtained when ozone reacts with lead sulphide.
3
22. Complete the following equations:
i) 2F2 + 2H2O ¾¾
®
ii) H2S + Cl2 ¾¾
®
iii) 8NH3 (excess) + 3Cl2 ¾¾
3
® st row transition series that
23. Name the metal of the 1
i) has highest value for M2+ / M standard electrode potential ii) has zero spin only magnetic moment in its +2 oxidation state. iii) exhibit maximum number of oxidation states.
3
24. Write ionic equations for the reaction of dichromate ions with
i) hydroxyl ions ii) Fe+2 ions in acidic medium
In which one of the two reactions will the oxidation number of chromium remains same?
3
2-.
25. Using VBT account for the geometry and magnetic property of [Ni(CN)4]
Given atomic number of Ni =28.
3
26. Give the IUPAC name of [Co Cl2 (NH3)4]Cl. Draw cis and trans isomers of
[Co Cl2 (NH3)4]+ ion.
PART-D
IV. Answer any THREE of the following. (each question carries 5 marks) 3x5=15
27. What is packing efficiency in a crystal? Draw the unit cell of a simple cubic lattice and calculate the packing efficiency in a simple cubic lattice.
5
28. a) Vapour pressure of liquids A and B at 298 K is 300 mm of Hg and 450 mm of Hg respectively. If the total vapour pressure of a mixture of A and B is 405 mm of Hg, calculate the mole fraction of A in the mixture.
b) What happens to the solubility of a gas in a liquid with increase in temperature? Give reason.
3+2
29. a) Calculate the equilibrium constant of the reaction at 298 K.
Mg(s) + 2Ag+(aq) ¾¾ Mg+2 (aq) + 2Ag (s) ; E 0 = +3.16 V
®
cell

30.

b) How is molar conductivity related to the conductivity of a solution? Which one of these has higher molar conductivity:0.1 M KCl or 0.01 M KCl? 3+2
a) The rate of a reaction increases by 4 times when the temperature of the reaction is raised from 340 K to 360 K. Calculate the energy of activation of the reaction. Given R = 8.314 J/K/mol.
b) Draw a graph of potential energy versus reaction coordinate to show the effect of catalyst on activation energy.
3+2

31.

a) What is coagulation of a sol? Name two methods by which a lyophobic sol can be coagulated.
b) What is the change in enthalpy and entropy during adsorption of gas in a solid? 3+2
V. Answer any FOUR of the following. (Each question carries 5 marks)
4x5=20
32. a) Mention the major product formed in the following reactions: alc.KOH,D i) 2-bromopentane ¾¾¾¾
®
ii)
b)
33.

a)
b)

34.

a)

b)

35.

a)
b)

36.

a)

37.

b)
a)
b)

anhyd. AlCl3
+ CH3-CO-Cl ¾¾¾¾®

D iii) C2H5Br + AgCN ¾¾
3+2
®
Write the equations for the steps in SN1 mechanism of the conversion of tertbutyl bromide into tert-butyl alcohol.
Give equations for:
i) Kolbe’s reaction ii) Williamson’s ether synthesis
An organic compound (P) with the formula C3H6O reacts with CH3MgX followed by hydrolysis forms an alcohol (Q), which does not undergo dehydrogenation? Name the compounds P and Q.
3+2
Write equations for:
i) Gattermann-Koch reaction to convert benzene into benzaldehyde. ii) the formation of oxime from carbonyl compounds iii) the reaction between carboxylic acid and PCl5.
Give reasons:
i) a-hydrogen atoms of aldehydes and ketones are acidic. ii) An electron donating group decreases the acid strength of carboxylic acid. 3+2
Br2 / NaOH
NaNO 2 ,HCl
i) C6H5CONH 2 ¾¾¾¾ X. ii) X ¾¾¾¾® Y. What are X and Y? Name the
®
0° C

reaction occurring in step (i).
Arrange the following in the increasing order of their basic strengths in the aqueous medium: (CH3)3N, NH3, CH3NH 2, (CH3)2NH. Give one reason for the trend observed.
3+2
Mention two differences in the structure of starch and cellulose. Write the
Haworth’s structure of the monomer in cellulose.
Give an example each for i) acidic a-amino acid ii) fibrous protein.
3+2
How are condensation polymers formed? Give an example with an equation.
With respect to natural rubber:
i) name its monomer ii) name the element used for vulcanization.
3+2

Scheme of valuation for model question paper-1
Note: Any other correct alternate answer can be honoured wherever applicable.

Q.N

Value Points

I.

Marks
PART-A

1

Any one out of the four

1

2

1

3

Extent of association OR dissociation of a solute
A cell that can be recharged again

4

t½ gets doubled OR becomes 2 times the original

1

5

Manganese dioxide or MnO2

1

6

Cu2S + FeS

1

7

Linear

1

8

Rotation by an enantiomer is cancelled by the other

1

9

triiodomethane

1

Sequence of a-amino acids in a polypeptide chain

1

10
II.

1

PART-B

11

Schottky defect

Frenkel defect

i. Density decreases

i. No change in density.

ii. Observed when cations and anions ii. Observed when cations and have similar size. anions differ in their size. iii. Equal number of cations and iii. The smaller ion gets anions are missing from lattice dislocated from its lattice points point

Any two

2

12

Anode – Chlorine ; Cathode – Hydrogen

13

27 times
No change in the order

1
1

14

i) Due to comparable energies of 5f, 6d and 7s levels.

1

ii) It is due to Lanthanoid contraction.

1

Conc. HCl + ZnCl2

1

tertiary alcohol

1

Esterification
R-COOH + R1OH ¾¾ RCOOR1 + H2O
®

1

They prevent spoilage of food.

1

Table salt or sugar or sodium benzoate (any one)

1

15
16
17
18

Anionic, cationic, non-ionic (any two)

(1+1)

2

1

(1+1)

2

III.

PART-C

19

i) Bauxite is concentrated by digesting the powdered ore in a concentrated solution of sodium hydroxide at 473-573 K and 35 bar pressure. Al2O3 is leached as sodium aluminate.

1

ii) Aluminate solution is neutralised by passing CO2. Hydrated Al2O3 is precipitated by seeding.

1
1

iii) Hydrated Al2O3 is filtered, dried and heated to get pure Al2O3.
20

1
1
1

X is PCl5
Y is H3PO4
Basicity of Y is 3.

22

A slow dry stream of oxygen is passed through a silent electrical discharge. Some oxygen gets converted into ozone.
3O2 ¾¾ 2O3
®

1

Lead sulphate

21

1
1
1
1

i) ¾¾ 4HF + O2
®
ii) ¾¾ 2HCl + S
®
iii) ¾¾ 6NH4Cl + N2
®

23

1
1
1

i) Copper ii) Zinc iii) Manganese

24

1

2
2
i) Cr2 O7 - + 2OH - ¾¾ 2CrO 4 - + H 2 O
®
2 ii) Cr2 O7 - + 14H + + 6Fe2 + ¾¾ 2Cr 3+ + 6Fe3+ + 7H 2 O
®

1
1
1

In reaction (i)

1

25

1

1

Geometry: square planar
26

tetraamminedichloridocobalt(III) chloride

1

2

IV.
27

PART-D
It is a percentage of total space filled by the particles in a crystal.

Edge length or side of a cube = a, radius of a particle = r
Particles touch each other along the edge
\ a = 2r, volume of the cell = a3 = 8r3

1
1

1

Simple cubic unit cell contains only 1 atom
4 3
Volume occupied = pr 3 volume of one atom
Packing efficiency =
´ 100% volume of the unit cell

4 3 pr 3
´ 100 = 52.4%
8r 3
28a. Let mole fraction of A be xA ; mole fraction B ; xB = (1 - xA)
From Raoult’s law p 0 xA + p 0 xB = Ptotal OR p 0 xA + p 0 (1 - xA) = Ptotal
A
B
A
B
=

300 xA + 450 (1 - xA) = 405 xA = 0.3
It decreases.
b.
Dissolution of a gas in a liquid is an exothermic process.
29a. E 0 = 0.059 log KC cell n
0.059
3.16 = log KC
2
KC = 1.314 ´ 10107 k b.
Lm =
C
0.01 M KCl k Ea é T2 - T1 ù
30a.
log 2 = ê ú k1 2.303R ë T1T2 û
Ea
é 360 - 340 ù log 4 =
2.303 ´ 8.314 ê 360 ´ 340 ú ë û

1

1

1
1
1
1
1
1
1
1
1
1
1
1
1

Ea = 70554 J or 70.554 kJ
(Answer without unit, deduct 1 mark)
b.

2
31a. The process of settling of colloidal particles is called coagulation of the sol.

1

By electrophoresis OR by boiling OR by adding an electrolyte OR by mixing two oppositely charged sols. (Any two)

2

b.

Enthalpy decreases OR DH is negative.
Entropy decreases OR DS is negative.

1
1

V.
32a. i) CH3 - CH = CH-CH2-CH3

or pent-2-ene

1

ii)

or

4-chloroacetophenone
1

iii) C2H5NC or ethylisocyanide or ethylisonitrile or ethylcarbylamine
1
b.

Step-1:
1
(CH3)3CBr ¾¾
®

+ Br-

Step-2:
+ -OH ¾¾ (CH3)3C OH
®

1

33a. i) Kolbe’s reaction: Sodium phenate undergoes electrophile substitution reaction with
CO2
a weak electrolyte, finally to form orthohydroxybenzoic acid as main product.

1

1
OR
2

ii) Alkyl halide reacts with sodium alkoxide to form ether
1
1

R-X + Na-O-R ¾¾ R-O-R + NaX
®
OR
R-X
Alkyl halide
b.
34a.

b.

+

Na-O-R

¾¾
®

Sodium alkoxide

R-O-R

+

NaX

ether

P is acetone
Q is tert-butyl alcohol
i)
ii) iii) R-COOH + PCl5 ¾¾ R-COCl + POCl3 + HCl
®
i) It is due to strong electron withdrawing effect of carbonyl group and resonance stabilisation of conjugate base.
OR

2
1
1
1
1
1

1

ii) An electron donating group destabilises the carboxylate anion or the conjugate base.
OR

35a. X is C6H5NH 2
Y is C6H5N2Cl.
Hoffmann’s bromamide degradation reaction
b.

(CH3)2 NH > CH3NH2 > (CH 3)3 N > NH3
Inductive effect or solvation effect or steric hindrance

36a.

Starch

1

1
1
1
1
1

Cellulose

1. Made up of a-D(+) glucose units
2. Has a-glycosidic linkage.

1. Made up of b-D(+) glucose units 3. Has C1-C4 and C1-C6 linkages.

2. Has b-glycosidic linkage.

4. Has linear and polymeric chains.

branched 3. Has only C1-C4 linkages.
4. It is a linear polymer.

Any two

2

1
b.

i) Aspartic acid ii) Keratin

OR

OR

1
1

glutamic acid.

myosin

37a. Condensation polymers are formed by repeated condensation reaction between two different bifunctional monomeric units.

1
1

E.g.: Nylon 6, 6 nH2N(CH2)6NH 2 + nHOOC (CH2)4 COOH ¾¾
®
[ NH(CH2)6NHCO(CH 2)4CO ]

n

+ (n - 1) H2O

1

Any other suitable example with equation.
b.

i) Isoprene OR ii) Sulphur

2-methyl – 1, 3 -butadiene

1
1