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B.Sc. (Part-II) Semester—III Examination
CHEMISTRY
Time : Three Hours] [Maximum Marks : 80
Note :— (1) Question No. 1 is compulsory.
(2) Solve ONE question from each unit.
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(3) Draw diagrams and give equations wherever necessary.
(4) Use of scientific calculator is allowed.
1. (A) Fill in the blanks :(— 4x½=2
(i) The property of metals to form thin sheets on hammering is known as __________
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(ii) LiAlH4 reduces the carbonyl group into __________ group.
(iii) The surface tension of liquid __________ with increase of the temperature.
(iv) The titration between an acid and the base is also called as __________
(B) Choose the correct alternative :— 4x½=2
(i) In conformational analysis of n-butane the highly stable conformation is :
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(a) Gauche (b) Anti or Skew
(c) Partially Eclipsed (d) Fully Eclipsed
(ii) The hybridisation of carbon and oxygen atoms in carbonyl group is :
(a) sp³ (b) sp
(c) sp² (d) dsp²
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(iii) The upper critical solution temperature of Phenol-water system is :
(a) 68.1 (b) 67.8
(c) 68.7 (d) 67.9
(iv) In gravimetric estimation the unknown compound is analysed by measuring its :
(a) Pressure (b) Volume
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(c) Density (d) Mass
(C) Answer the following in ONE sentence - — 4
(i) What is meant by resolution ?
(ii) What is phase transition ?
(iii) What are optically active compounds ?
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(iv) What is molality ?
UNIT—I
2. (A) Explain VSEPR theory with suitable example. 4
(B) How will you compare atomic orbitals with molecular orbitals ? 4
(C) Draw molecular orbital energy level diagram of O2 molecule. Calculate its bond order. 4
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OR
3. (P) How will you differentiate bonding and antibonding molecular orbitals ? 4
(Q) Discuss (i) metallic luster (ii) Electrical conductivity of metal on the basis of free electron theory. 4
(R) Discuss the structure of BF3 molecule on the basis of VSEPR theory. 4
UNIT—II
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4. (A) Calculate the mole fraction of ethanol and water, if solution contains 6 moles of ethanol and 3 moles of water 4
(B) Explain the terms :—
(i) Normality
(ii) Molality. 4
(C) Discuss the choice of suitable indicator in strong acid with weak base. 4
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OR
5. (B) Discuss the following steps involved in gravimetric estimation of Barium as barium Sulphate :
(i) Precipitation
(ii) Digestion. 4
(Q) Write a note on Iodimetry and Iodometry. 4
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(R) Explain :—
(i) End Point
(ii) Molarity. 4
UNIT—III
6. (A) Complete the following reactions :
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(i) H-C=CH + H2O -->
(B) How will you prepare acetone from
(i) Isopropyl alcohol
(ii) 2, 2-Dichloro propane ? 4
(C) What happens when Benzoic acid is treated with :
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(i) Ethyl alcohol in presence of conc. H2SO4
(ii) PCl5 in presence of conc. H2SO4 ? 4
OR
7. (P) How will you prepare
(i) Benzyl alcohol
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(ii) Phenyl cyanide. 4
(Q) What happens when
(i) Ethylene glycol on oxidation with chromic acid
(ii) Lactic acid reacts with ethanol in conc. H2SO4 ? 4
(R) Explain Aldol condensation in Aldehydes and Ketones with example. 4
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UNIT—IV
8. (A) Explain the following :
(i) Plane of symmetry
(ii) Centre of symmetry. 4
(B) Assign the following groups in proper priority order according to ‘R’ and ‘S’ nomenclature system :
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(i) —COOH, —NH2, —OH, —CH3
(ii) —C2H5, —OH, —H, —CH3 4
(C) What is geometrical isomerism ? Explain with suitable example. 4
OR
9. (P) Explain the conformational analysis of n-butane with energy level diagram. 4
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(Q) Explain the terms :
(i) Chirality
(ii) Racemisation. 4
(R) Classify the following compounds into E-Z type :
Br\ /Cl Br\ /H CH3-C\ /CH2 H CH3-C\ /CH2 -CH3
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CH3 Cl Cl Cl CH3 CH3 H
4
UNIT—V
10. (A) Explain the variation of Gibbs free energy with temperature and pressure. 4
(B) State and explain Nernst Distribution Law. State the conditions of its validity. 4
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(C) What is extraction ? Explain its types. 4
OR
11. (P) Derive Gibb’s—Duhem equation. 4
(Q) Explain the Phenol-Water system. 4
(R) The Value of Kp for Water
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CO(g) + H2O(g) = CO2(g) + H2(g)
is 1.6 x 10?³ at 25°C. Calculate the standard free energy change (?G°) of the reaction at 25°C,
(R = 8.314 JK?¹ mole?¹) 4
UNIT—VI
12. (A) How relative viscosity of liquid is determined by Ostwald’s Viscometer ? 4
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(B) Define :—
(i) Cell constant
(ii) Molar conductance. 4
(C) 0.5 N solution of salt occupying volume between two platinum electrodes 0.0172 m apart and 0.04499 sq m. area has resistance 25 ohm. Calculate equivalent conductance of solution. 4
OR
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13. (P) What are the advantages of conductometric titrations over ordinary titrations ? 4
(Q) Explain the variation of specific and equivalent conductance with dilution. 4
(R) Describe moving boundary method for determination of transport number. 4
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