NEET Thermodynamics — Set 18

Question 1

A gas undergoes a cyclic process where $ 600 \, \text{J} $ of heat is absorbed. What is the net work done by the gas?

Accepted Answer

For a cyclic process, $ \Delta U = 0 $. $ \Delta Q = \Delta U + \Delta W \Rightarrow 600 = 0 + \Delta W $. $ \Delta W = 600 \, \text{J} $.

Question 2

What is the change in internal energy for $ 0.5 \, \text{moles} $ of an ideal gas heated from $ 250 \, \text{K} $ to $ 300 \, \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 = 0.5 $, $ C_v = 20.8 $, $ \Delta T = 300 - 250 = 50 $. $ \Delta U = 0.5 \times 20.8 \times 50 = 520 \, \text{J} $.

Question 3

How much heat is required to raise the temperature of $ 1 \, \text{kg} $ of copper from $ 20^\circ \text{C} $ to $ 50^\circ \text{C} $? (Specific heat of copper = $ 386.4 \, \text{J kg}^{-1} \text{K}^{-1} $)

Accepted Answer

Heat capacity: $ \Delta Q = m s \Delta T $. $ m = 1 \, \text{kg} $, $ s = 386.4 \, \text{J kg}^{-1} \text{K}^{-1} $, $ \Delta T = 50 - 20 = 30 \, \text{K} $. $ \Delta Q = 1 \times 386.4 \times 30 = 11592 \, \text{J} $.

NEET Physics: Thermodynamics — Practice Set 18

Q1. A gas undergoes a cyclic process where \( 600 \, \text{J} \) of heat is absorbed. What is the net work done by the gas?

Q2. What is the change in internal energy for \( 0.5 \, \text{moles} \) of an ideal gas heated from \( 250 \, \text{K} \) to \( 300 \, \text{K} \) at constant volume? (\( C_v = 20.8 \, \text{J mol}^{-1} \text{K}^{-1} \))

Q3. How much heat is required to raise the temperature of \( 1 \, \text{kg} \) of copper from \( 20^\circ \text{C} \) to \( 50^\circ \text{C} \)? (Specific heat of copper = \( 386.4 \, \text{J kg}^{-1} \text{K}^{-1} \))

Q4. An ideal gas expands isothermally at \( 460 \, \text{K} \) from \( 3 \, \text{L} \) to \( 9 \, \text{L} \) with \( 0.5 \, \text{moles} \). What is the work done by the gas? (\( R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} \))

Q5. How much heat is required to raise the temperature of \( 0.6 \, \text{kg} \) of silver from \( 20^\circ \text{C} \) to \( 50^\circ \text{C} \)? (Specific heat of silver = \( 236.1 \, \text{J kg}^{-1} \text{K}^{-1} \))

Q6. What is the molar specific heat capacity at constant pressure for a solid if its molar specific heat is \( 24.4 \, \text{J mol}^{-1} \text{K}^{-1} \) at constant volume?

Q7. What is the molar specific heat capacity at constant pressure for a diatomic gas if \( C_v = 20.75 \, \text{J mol}^{-1} \text{K}^{-1} \) and \( R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} \)?

Q8. A gas undergoes an adiabatic expansion from \( 25 \, \text{L} \) to \( 100 \, \text{L} \), reducing its pressure from \( 16 \, \text{atm} \) to \( 1 \, \text{atm} \). What is the value of \( \gamma \)?

Q9. A system in a cyclic process absorbs \( 1020 \, \text{J} \) of heat and rejects \( 380 \, \text{J} \). What is the net work done?

Q10. A system in a cyclic process absorbs \( 900 \, \text{J} \) of heat and rejects \( 400 \, \text{J} \). What is the net work done?