NEET Thermodynamics — Set 7

Question 1

Which of the following statements is correct about an isothermal process for an ideal gas?

Accepted Answer

In an isothermal process ($ T = \text{constant} $), the internal energy of an ideal gas ($ U $, temperature-dependent) remains constant ($ \Delta U = 0 $), and heat supplied equals work done ($ \Delta Q = \Delta W $), making option C correct.

Question 2

A diatomic gas undergoes an adiabatic expansion from $ 780 \, \text{K} $ to $ 390 \, \text{K} $ with $ 1.3 \, \text{moles} $. What is the work done? ($ R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} $, $ \gamma = 1.4 $)

Accepted Answer

$ W = \frac{\mu R (T_1 - T_2)}{\gamma - 1} $. $ \mu = 1.3 $, $ R = 8.3 $, $ T_1 = 780 $, $ T_2 = 390 $, $ \gamma = 1.4 $. $ W = \frac{1.3 \times 8.3 \times (780 - 390)}{1.4 - 1} = \frac{10.79 \times 390}{0.4} = 10520.25 \, \text{J} \approx 10520 \, \text{J} $.

Question 3

How much heat is required to raise the temperature of $ 0.15 \, \text{kg} $ of copper from $ 40^\circ \text{C} $ to $ 60^\circ \text{C} $? (Specific heat of copper = $ 386.4 \, \text{J kg}^{-1} \text{K}^{-1} $)

Accepted Answer

$ \Delta Q = m s \Delta T $. $ m = 0.15 $, $ s = 386.4 $, $ \Delta T = 60 - 40 = 20 $. $ \Delta Q = 0.15 \times 386.4 \times 20 = 1159.2 \, \text{J} \approx 1159 \, \text{J} $.

NEET Physics: Thermodynamics — Practice Set 7

Q1. Which of the following statements is correct about an isothermal process for an ideal gas?

Q2. A diatomic gas undergoes an adiabatic expansion from \( 780 \, \text{K} \) to \( 390 \, \text{K} \) with \( 1.3 \, \text{moles} \). What is the work done? (\( R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} \), \( \gamma = 1.4 \))

Q3. How much heat is required to raise the temperature of \( 0.15 \, \text{kg} \) of copper from \( 40^\circ \text{C} \) to \( 60^\circ \text{C} \)? (Specific heat of copper = \( 386.4 \, \text{J kg}^{-1} \text{K}^{-1} \))

Q4. How many joules are equivalent to \( 250 \, \text{cal} \) of heat? (1 cal = \( 4.186 \, \text{J} \))

Q5. How much heat is required to vaporize \( 0.5 \, \text{g} \) of water at \( 100^\circ \text{C} \) and \( 1 \, \text{atm} \)? (Latent heat = \( 2256 \, \text{J/g} \))

Q6. A system releases \( 720 \, \text{J} \) of heat and has \( 180 \, \text{J} \) of work done on it. What is the change in internal energy?

Q7. In an isobaric process, \( 1.4 \, \text{moles} \) of an ideal gas expand from \( 5 \, \text{L} \) to \( 11 \, \text{L} \) at \( 370 \, \text{K} \). What is the work done by the gas? (\( R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1} \))

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

Q9. Which of the following statements is incorrect about the Zeroth Law of Thermodynamics?

Q10. 0.1 kg of a substance absorbs 1200 J of heat, increasing its temperature from 20°C to 50°C. What is its specific heat capacity?