B.Sc. 1st Part Pre Examination Test 2021

Chemistry Subsidiary
Time: 3 Hours
Full Marks: 75

Answer any five questions. Selecting not more than two questions from any group.

Group-A

1. a. Deduce law of corresponding state. 7
b. What is critical constants. Derive their values in terms of vander waal constants ‘a’ and ‘b’. 8

2. a. Explain molar, Equivalent and Specific Conductance of an electrolytic solution. 6
b. What is the effect of dilution on molar, Equivalent and Specific Conductance. 3
c. Explain Kohlrausch law. 3
d. Calculate the limiting molar conductivity of CH₃COOH which is a weak electrolyte. The molar conductivities of CH₃COONa, HCl and NaCl at infinite dilution are 90.1S.cm²/mol, 426.16S.cm²/mol and 126.45S.cm²/mol respectively. 3

3. Explain any three of the followings- 3 x 4
a. Unit Cell and Crystal Lattice
b. Brownian Motion
c. Surface Tension
d. Phase Rule

Group-B

4. a. Explain Bohr’s atomic model 5
b. Derive an expression of Bohr’s energy and radius of an electron 10

5. a. Give hybridization, structure and shape of the followings- 3 x 2
ClF₃, XeO₂F₂ and I₃^-
b. Expalin hydrogen bond and their types with examples 4
c. Expalin the following- 2.5 x 2
i. Diploe moment of NF₃ is less than that of NH₃.
ii. 1st I.P. of oxygen is less than that of nitrogen.

6. a. Give the preparation, properties and structure of Borazine or hydrogen peroxide.8
b. Explain Heisenberg uncertainty principle and de Broglie wave equation.7

Group-C

7. a. How will you determine the molecular weight of a base by H₂PtCl₆ method. 7
b. How will you distinguish - 2 x 4
i. Ethane and Ethyne
ii. Acetaldehyde and Acetone
iii. Formic acid and Acetic acid
iv. Formaldehyde and Acetaldehyde

8. a .Explain the following reactions- 3 x 3
i. Aldol Condensation
ii. Diels Alder Reaction
iii. Hoffmann Bromamide Reaction
b. Explain why- 3 x 2
i. Phenol is more acidic than ethanol
ii. Chloroacetic acid is more acidic than acetic acid

9. a. Write short notes on the followings- 3 x 4
i. Inductive effect
ii. Hyperconjugation
iii. Resonance
b. Explain geometrical isomerism with suitable examples.3