NEET Thermodynamics — Set 21

Question 1

In a reversible process, what condition must be met regarding the system and surroundings?

Accepted Answer

A process is reversible if it can be reversed, returning both the system and surroundings to their original states without any net change elsewhere. This requires quasi-static conditions and no dissipative effects like friction.

Question 2

How much heat is required to raise the temperature of $ 0.2 \, \text{kg} $ of aluminium from $ 45^\circ \text{C} $ to $ 75^\circ \text{C} $? (Specific heat of aluminium = $ 900 \, \text{J kg}^{-1} \text{K}^{-1} $)

Accepted Answer

$ \Delta Q = m s \Delta T $. $ m = 0.2 $, $ s = 900 $, $ \Delta T = 75 - 45 = 30 $. $ \Delta Q = 0.2 \times 900 \times 30 = 5400 \, \text{J} $.

Question 3

0.3 moles of an ideal gas at 400 K expand adiabatically from 6 atm to 2 atm. If $ \gamma = 1.5 $, what is the final temperature?

Accepted Answer

Adiabatic: $ T_1 V_1^{\gamma-1} = T_2 V_2^{\gamma-1} $, $ P V = \mu R T \Rightarrow V_1 = \frac{\mu R T_1}{P_1} = \frac{0.3 \times 8.3 \times 400}{6} = 166 \, \text{L} $, $ V_2 = \frac{0.3 \times 8.3 \times T_2}{2} = 1.245 T_2 $. $ 400 \times 166^{0.5} = T_2 \times (1.245 T_2)^{0.5} $. Solve iteratively or approximate: $ T_2 \approx 318 \, \text{K} $ (via $ P V^\gamma $).

NEET Physics: Thermodynamics — Practice Set 21

Q1. In a reversible process, what condition must be met regarding the system and surroundings?

Q2. How much heat is required to raise the temperature of \( 0.2 \, \text{kg} \) of aluminium from \( 45^\circ \text{C} \) to \( 75^\circ \text{C} \)? (Specific heat of aluminium = \( 900 \, \text{J kg}^{-1} \text{K}^{-1} \))

Q3. 0.3 moles of an ideal gas at 400 K expand adiabatically from 6 atm to 2 atm. If \( \gamma = 1.5 \), what is the final temperature?

Q4. Which of the following statements is correct about \( C_p \) and \( C_v \) for an ideal gas?

Q5. In an isobaric process, \( 0.9 \, \text{moles} \) of gas expand from \( 360 \, \text{K} \) to \( 450 \, \text{K} \). What is the heat supplied if \( C_p = 25.5 \, \text{J mol}^{-1} \text{K}^{-1} \)?

Q6. A gas expands adiabatically from \( 5 \, \text{atm} \) and \( 10 \, \text{L} \) to \( 1 \, \text{atm} \). What is the final volume? (\( \gamma = 1.33 \))

Q7. Which of the following statements is correct about irreversible processes?

Q8. A gas at 6 atm in an 8 L container is cooled from 50°C to 10°C at constant volume. What is the final pressure?

Q9. What is the molar specific heat capacity at constant pressure for a monatomic gas if \( R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} \)?

Q10. How much heat is required to raise the temperature of \( 0.5 \, \text{kg} \) of carbon from \( 25^\circ \text{C} \) to \( 55^\circ \text{C} \)? (Specific heat of carbon = \( 600 \, \text{J kg}^{-1} \text{K}^{-1} \))