NEET Thermodynamics — Set 13

Question 1

A system in a cyclic process absorbs $ 650 \, \text{J} $ of heat and performs $ 200 \, \text{J} $ of work. What is the heat rejected?

Accepted Answer

For cyclic: $ \Delta U = 0 $, $ Q_{\text{net}} = W $. $ Q_{\text{absorb}} - Q_{\text{reject}} = W $. $ 650 - Q_{\text{reject}} = 200 \Rightarrow Q_{\text{reject}} = 650 - 200 = 450 \, \text{J} $.

Question 2

A gas undergoes an adiabatic compression with 400 J of work done on it. What is the change in internal energy?

Accepted Answer

Adiabatic: $ \Delta Q = 0 $, $ \Delta U = -\Delta W $. Work on system: $ \Delta W = -400 \, \text{J} $. $ \Delta U = -(-400) = 400 \, \text{J} $.

Question 3

Which of the following statements is correct about internal energy?

Accepted Answer

Internal energy ($ U $) is a state function, dependent on the system’s state (e.g., temperature for an ideal gas), not the path taken. Option A is correct.

NEET Physics: Thermodynamics — Practice Set 13

Q1. A system in a cyclic process absorbs \( 650 \, \text{J} \) of heat and performs \( 200 \, \text{J} \) of work. What is the heat rejected?

Q2. A gas undergoes an adiabatic compression with 400 J of work done on it. What is the change in internal energy?

Q3. Which of the following statements is correct about internal energy?

Q4. A gas undergoes an adiabatic expansion from \( 10 \, \text{L} \) to \( 40 \, \text{L} \), reducing its pressure from \( 8 \, \text{atm} \) to \( 1 \, \text{atm} \). What is the value of \( \gamma \)?

Q5. A gas at 3 atm in a 4 L container is heated from 25°C to 75°C at constant volume. What is the final pressure?

Q6. Which of the following is NOT a state variable in thermodynamics?

Q7. An ideal gas absorbs \( 1000 \, \text{J} \) of heat in an isochoric process, increasing its temperature by \( 20 \, \text{K} \). What is the number of moles of the gas? (\( C_v = 20 \, \text{J mol}^{-1} \text{K}^{-1} \))

Q8. A gas undergoes an adiabatic expansion, doing 450 J of work. What is the change in its internal energy?

Q9. A system absorbs \( 830 \, \text{J} \) of heat and has \( 290 \, \text{J} \) of work done on it. What is the change in internal energy?