Important Questions for CSIR NET Chemical Science - PHYSICAL CHEMISTRY-PART III

Most Important Questions on Physical Chemistry - Part III (Download PDF)

1. 

Having a rate constant k₁ = 10^-1 s^-1

k₂ = 10^-2 s^-1

If the initial concentration is 10 M. Calculate the concentration of A after 0.1 seconds.

1. 9.9
2. 3.0
3. 4.6
4. 8.9

2. Calculate the entropy change that is accompanied by the freezing of one mole of water at 25°C to ice at –10°C; given that the heat of fusion of ice at its fusion point (0°C) is 6.00 kJ mol–1, the heat capacity of ice is 36.82 J K–1 mol–1 and heat capacity of liquid water is 75.31 J K–1 mol–1.

1. -25.23 J/K mol
2. -32 .30 J/K mol
3. -20.45 J/K mol
4. -29.96 J/K mol

3. The mass x of a solute adsorbed per gram of a solid adsorbed is given by the Freundlich adsorption isotherm as x = kcn, here k and n are 0.160 and 0.431, respectively. Calculate the amount of acetic acid (Mm = 60.05 g mol-1) that 1 kg of charcoal would adsorb from a 0.837 M vinegar solution.

1. 4.32 mol
2. 2.47 mol
3. 1.57 mol
4. 3.26 mol

4. Determine the mean activity coefficient of NaCl at a molality of 0.01 in an aqueous solution at 25° C.

1. 0.789
2. 0.889
3. 0.650
4. 0.899

5. Which statement is correct according to the Le-Chatelier principle for the following reaction PCl5(g) → PCl3 (g) + Cl2(g) when mixing of inert gas takes place at constant volume?

1. Equilibrium shifts towards the high molecular side.
2. Equilibrium shifts towards the lower molecular side.
3. Equilibrium shifts towards the high molecular side, and pressure increases into the reaction container.
4. Pressure increases in the reaction container, but equilibrium is unchanged.

6. Point group of optically active allene is:

1. C₂
2. C_s
3. C_2v
4. C_2h

7. Which of the following radiation is responsible for Rotational Raman Spectroscopy?

1. UV –Visible radiation
2. Infrared radiation
3. X- rays
4. Microwave radiations

8. Suppose the wave function of a one-dimensional system is Ѱ= sin(kx) exp (3ikx). In an experiment measuring the momentum of the system, one of the expected outcomes is?

1. 0
2. ħk
3. 2ħk
4. 3ħk

9. Sodium has a bcc structure with the nearest neighbour distance of 365.9 pm. Calculate its density (Atomic mass of sodium = 23).

1. 0.95 g cm-3
2. 0.12 g cm-3
3. 0.01 g cm-3
4. 1.51 g cm-3

10. At constant temperature and volume what will be the highest translational Molar Entropy?

1. Cl₂
2. Br₂
3. F₂
4. I₂

Solutions:

Solution 1. 

Solution 2.

Solution 3.

Solution 4.

Solution 5.

When mixing of inert gas takes place at constant volume, then the total pressure of the container is increased, but individual active mass or number of a mole per unit volume remains unchanged. So, the equilibrium condition will be unchanged.

Solution 6. 

Molecules with no improper axis of rotation are optically active. Note that S1 = σ and S2 = i. Point groups have no mirror planes, centres of inversion or other improper rotations are C1, Cn, and Dn. Therefore, optically active allene has C₂ point group.

Solution 7.

In rotational Raman spectroscopy, we use Infrared radiations. The selection rule for this is:

∆J = 0, +2, –2

For a molecule to be Rotational Raman active, it should be anisotropically polarisable, i.e its polarizability ellipsoid should change its radius on rotating the molecule.

Solution 8.

Solution 9. 

Solution 10.

Answer Key:

1. A
2. D
3. B
4. B
5. D
6. A
7. B
8. B
9. D
10. D

Download Important Questions On Physical Chemistry - Part III - Download PDF Here

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• Study Notes for CSIR NET Life Science - (Download PDF)
• Study Notes for CSIR NET Chemical Science - Download PDF Here!

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