NEET Thermodynamics — Set 11

Question 1

A system releases $ 550 \, \text{J} $ of heat and performs $ 200 \, \text{J} $ of work. What is the change in internal energy?

Accepted Answer

First Law: $ \Delta Q = \Delta U + \Delta W $. $ \Delta Q = -550 $ (heat released), $ \Delta W = 200 $ (work by system). $ -550 = \Delta U + 200 \Rightarrow \Delta U = -550 - 200 = -750 \, \text{J} $.

Question 2

What characteristic of a solid’s molecular structure leads to a molar specific heat capacity of approximately $ 3R $?

Accepted Answer

In solids, each atom vibrates with 3 degrees of freedom, contributing $ 3 k_B T $ (kinetic and potential) per atom. For a mole, this totals $ 3 R T $, so $ C = \frac{\Delta U}{\Delta T} = 3R $, due to vibrational motion.

Question 3

What is the key characteristic of a thermodynamic equilibrium state?

Accepted Answer

A system in thermodynamic equilibrium has constant macroscopic variables (e.g., pressure, volume, temperature) over time, indicating no net changes or flows within the system or with its surroundings.

NEET Physics: Thermodynamics — Practice Set 11

Q1. A system releases \( 550 \, \text{J} \) of heat and performs \( 200 \, \text{J} \) of work. What is the change in internal energy?

Q2. What characteristic of a solid’s molecular structure leads to a molar specific heat capacity of approximately \( 3R \)?

Q3. What is the key characteristic of a thermodynamic equilibrium state?

Q4. A solid has a molar specific heat capacity of \( 24.9 \, \text{J mol}^{-1} \text{K}^{-1} \). Which element could it be?

Q5. A gas at \( 4 \, \text{atm} \) and \( 27^\circ \text{C} \) in a \( 3 \, \text{L} \) container is cooled isochorically to \( -73^\circ \text{C} \). What is the final pressure?

Q6. Which of the following statements is correct about specific heat capacity?

Q7. In an isobaric process, \( 2 \, \text{moles} \) of an ideal gas expand from \( 10 \, \text{L} \) to \( 20 \, \text{L} \) at \( 400 \, \text{K} \). What is the work done by the gas? (Take \( R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} \))

Q8. What is the molar specific heat capacity at constant volume for a monatomic ideal gas? (Take \( R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} \))

Q9. Which of the following is a consequence of the Second Law of Thermodynamics?

Q10. A system in a cyclic process absorbs \( 860 \, \text{J} \) of heat and performs \( 340 \, \text{J} \) of work. What is the heat rejected?