CUET PG PYQs for Thermodynamics and Statistical Mechanics with Solutions: Practice CUET PG Previous Year Questions

1.

If the radiation emitted by a star has a maximum intensity at a wavelength of 446 nm, its surface temperature is approximately:

• 650 K
• 65 K
• 6500 K
• 65000 K

2.

Brewster's law can be expressed as:

• $\mu = \tan r$, where $\mu$ is the refractive index and $r$ is the angle of refraction
• $\tan i = \frac{1}{\mu}$, where $\mu$ is the refractive index and $i$ is the polarizing angle
• $\cos r = \mu$, where $\mu$ is the refractive index and $r$ is the angle of refraction
• $\mu = \tan i$, where $\mu$ is the refractive index and $i$ is the polarizing angle

3.

Ultraviolet light of wavelength 350 nm and intensity \(1.00Wm^{−2 }\) falls on a potassium surface. The maximum kinetic energy of the photoelectron is

• 3.3 eV
• 1.9 eV
• 3.2 eV
• 1.3 eV

4.

10g of water at \(100\degree C \)is converted into steam at the same temperature. If the latent heat of steam is 540cal/g, the change in entropy is

• 14.47 cal/K
• 144.7 cal/K
• 74.47 cal/K
• 47.47 cal/K

5.

Higher-energy photons are scattered from electrons initially at rest. Assume the photons are backscattered ($\theta = 180^\circ$) and their energies are much higher than the electron's rest mass energy. The wavelength shift will be $\frac{h}{m_e c} = 2.43 \times 10^{-12} \, \text{m}$.

• $4.86 \times 10^{-10} \, \text{m}$
• $48.6 \times 10^{-12} \, \text{m}$
• $4.86 \times 10^{-12} \, \text{m}$
• $0.486 \times 10^{-12} \, \text{m}$

6.

Which of the following statements are correct for the Second Law of Thermodynamics?
(A) It is impossible to derive a continuous supply of energy from a body by cooling it below the temperature of its surroundings.
(B) It is possible to derive a continuous supply of energy from a body by cooling it below the temperature of its surroundings.
(C) It is impossible for a self-acting machine, unaided by any external agency, to convey heat from a body at lower temperature to another body at higher temperature.
(D) It is possible for a self-acting machine, unaided by any external agency, to convey heat from a body at lower temperature to another body at higher temperature.
Choose the correct answer from the options given below:

• (A) and (B) only
• (B) and (C) only
• (B) and (D) only
• (A) and (C) only

7.

Which of the following statements are true for Compton effect?
(A) The wavelength of the scattered X-rays is larger than that of the incident X-rays.
(B) The change in wavelength depends on the intensity of the incident X-rays.
(C) The change in wavelength depends on the scattering angle.
(D) The wavelength of the scattered X-rays is smaller than that of the incident X-rays
Choose the correct answer from the options given below

• A and B are correct
• B and C are correct
• A and D are correct
• A and C are correct

8.

Match List I with List II:

List I	List II
(A) (∂S/∂P)T	(I) (∂P/∂T)V
(B) (∂T/∂V)S	(II) (∂V/∂S)P
(C) (∂T/∂P)S	(III) -(∂V/∂T)P
(D) (∂S/∂V)T	(IV) -(∂P/∂S)V

Choose the correct answer from the options given below:

• A-III, B-IV, C-II, D-I
• A-II, B-IV, C-III, D-I
• A-I, B-II, C-III, D-IV
• A-IV, B-III, C-II, D-I

9.

Which of the following is true for a reversible process

• The pressure and temperature of the working substance and the surroundings should differ at any stage
• The process should take place very slowly during operation.
• The process should take place very fast during operation
• Energy should be lost due to conduction or radiation during operation

10.

X-ray of wavelength 10.0 pm are scattered from a target in a Compton exper iment. If the X-rays are scattered through \(45\degree\), the scattered wavelength is

• 1.07 pm
• 70.1 pm
• 10.7 pm
• 107 pm

11.

The inter-molecular distance between two atoms of a hydrogen molecule is $0.77 \, \text{\AA}$, and the mass of a proton is $1.67 \times 10^{-27} \, \text{Kg}$. The moment of inertia of a molecule is:

• $4.95 \times 10^{-47} \, \text{Kg·m}^2$
• $0.495 \times 10^{-47} \, \text{Kg·m}^2$
• $4.5 \times 10^{-47} \, \text{Kg·m}^2$
• $45.9 \times 10^{-47} \, \text{Kg·m}^2$

12.

Consider phosphorus doping in silicon, for $T = 300 \, \text{K}$, at concentration $N_d = 10^{16} \, \text{cm}^{-3}$. The fraction of total electrons still in the donor states is:

• 41
• 41
• 41
• 14

13.

If the resonance frequency of an acoustic system is 300Hz and the half-power frequencies are 150Hz and 450Hz, the quality factor is:

• 1.25
• 1.5
• 1
• 1.75

14.

The efficiency of Carnot’s engine working between the steam point and the ice point is:

• 0.268
• 0.0268
• 0.628
• 0.826

15.

Clausius-Clapeyron’s latent heat equation is represented as: