NEET Thermodynamics — Set 5

Question 1

Which condition is essential for a process to be considered reversible?

Accepted Answer

A reversible process requires the absence of dissipative effects (e.g., friction, viscosity), allowing the system and surroundings to return to their original states. Quasi-static conditions alone are insufficient without eliminating dissipation.

Question 2

What is the change in internal energy for $ 0.4 \, \text{moles} $ of an ideal gas heated from $ 290 \, \text{K} $ to $ 330 \, \text{K} $ at constant volume? ($ C_v = 20.8 \, \text{J mol}^{-1} \text{K}^{-1} $)

Accepted Answer

$ \Delta U = \mu C_v \Delta T $. $ \mu = 0.4 $, $ C_v = 20.8 $, $ \Delta T = 330 - 290 = 40 $. $ \Delta U = 0.4 \times 20.8 \times 40 = 332.8 \, \text{J} \approx 333 \, \text{J} $.

Question 3

A system absorbs $ 500 \, \text{J} $ of heat and does $ 200 \, \text{J} $ of work. What is the change in its internal energy?

Accepted Answer

First Law: $ \Delta Q = \Delta U + \Delta W $. Given: $ \Delta Q = 500 \, \text{J} $, $ \Delta W = 200 \, \text{J} $. $ 500 = \Delta U + 200 $. $ \Delta U = 500 - 200 = 300 \, \text{J} $.

NEET Physics: Thermodynamics — Practice Set 5

Q1. Which condition is essential for a process to be considered reversible?

Q2. What is the change in internal energy for \( 0.4 \, \text{moles} \) of an ideal gas heated from \( 290 \, \text{K} \) to \( 330 \, \text{K} \) at constant volume? (\( C_v = 20.8 \, \text{J mol}^{-1} \text{K}^{-1} \))

Q3. A system absorbs \( 500 \, \text{J} \) of heat and does \( 200 \, \text{J} \) of work. What is the change in its internal energy?

Q4. An ideal gas expands isothermally at \( 570 \, \text{K} \) from \( 12 \, \text{L} \) to \( 36 \, \text{L} \) with \( 0.4 \, \text{moles} \). What is the work done by the gas? (\( R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} \))

Q5. Which property of an ideal gas simplifies its internal energy calculation?

Q6. Which of the following correctly describes the concept of heat?

Q7. A system absorbs \( 450 \, \text{J} \) of heat and performs \( 150 \, \text{J} \) of work. What is the change in internal energy?

Q8. What does the Clausius statement of the Second Law imply?

Q9. Why does the First Law of Thermodynamics allow some processes that the Second Law prohibits?

Q10. What is the change in internal energy for \( 0.5 \, \text{moles} \) of an ideal gas heated from \( 260 \, \text{K} \) to \( 310 \, \text{K} \) at constant volume? (\( C_v = 20.8 \, \text{J mol}^{-1} \text{K}^{-1} \))