NEET Thermal Properties of Matter — Set 1

Question 1

A gas at $ 3.5 \, \text{atm} $ and $ 77^\circ \text{C} $ occupies $ 4.5 \, \text{L} $. If the temperature drops to $ 27^\circ \text{C} $ and volume increases to $ 6 \, \text{L} $, what is the final pressure?

Accepted Answer

Given: $ P_1 = 3.5 \, \text{atm} $, $ T_1 = 77^\circ \text{C} = 350 \, \text{K} $, $ V_1 = 4.5 \, \text{L} $, $ T_2 = 27^\circ \text{C} = 300 \, \text{K} $, $ V_2 = 6 \, \text{L} $. $ \frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2} $. $ P_2 = P_1 \times \frac{V_1}{V_2} \times \frac{T_2}{T_1} = 3.5 \times \frac{4.5}{6} \times \frac{300}{350} = 3.5 \times 0.75 \times 0.8571 \approx 2.25 \, \text{atm} $.

Question 2

A silver sheet has an area of $ 1.5 \, \text{m}^2 $ at $ 20^\circ \text{C} $. What is the increase in area when heated to $ 120^\circ \text{C} $? ($ \alpha_l = 1.9 \times 10^{-5} \, \text{K}^{-1} $)

Accepted Answer

Given: $ A_0 = 1.5 \, \text{m}^2 $, $ \Delta T = 120 - 20 = 100^\circ \text{C} $, $ \alpha_l = 1.9 \times 10^{-5} \, \text{K}^{-1} $. $ \Delta A = A_0 \times 2 \alpha_l \Delta T = 1.5 \times 2 \times 1.9 \times 10^{-5} \times 100 = 0.0057 \, \text{m}^2 $.

Question 3

A gas occupies $ 4.2 \, \text{L} $ at $ 1.4 \, \text{atm} $ and $ 47^\circ \text{C} $. If the pressure is increased by $ 0.6 \, \text{atm} $ and temperature decreased by $ 20^\circ \text{C} $, what is the new volume?

Accepted Answer

Given: $ V_1 = 4.2 \, \text{L} $, $ P_1 = 1.4 \, \text{atm} $, $ T_1 = 47^\circ \text{C} = 320 \, \text{K} $, $ P_2 = 1.4 + 0.6 = 2 \, \text{atm} $, $ T_2 = 47 - 20 = 27^\circ \text{C} = 300 \, \text{K} $. $ \frac{P_1 V_1}{T_1} = \frac{P_2 V_2}{T_2} $. $ V_2 = V_1 \times \frac{P_1}{P_2} \times \frac{T_2}{T_1} = 4.2 \times \frac{1.4}{2} \times \frac{300}{320} = 4.2 \times 0.7 \times 0.9375 \approx 2.76 \, \text{L} $.

NEET Physics: Thermal Properties of Matter — Practice Set 1

Q1. A gas at \( 3.5 \, \text{atm} \) and \( 77^\circ \text{C} \) occupies \( 4.5 \, \text{L} \). If the temperature drops to \( 27^\circ \text{C} \) and volume increases to \( 6 \, \text{L} \), what is the final pressure?

Q2. A silver sheet has an area of \( 1.5 \, \text{m}^2 \) at \( 20^\circ \text{C} \). What is the increase in area when heated to \( 120^\circ \text{C} \)? (\( \alpha_l = 1.9 \times 10^{-5} \, \text{K}^{-1} \))

Q3. A gas occupies \( 4.2 \, \text{L} \) at \( 1.4 \, \text{atm} \) and \( 47^\circ \text{C} \). If the pressure is increased by \( 0.6 \, \text{atm} \) and temperature decreased by \( 20^\circ \text{C} \), what is the new volume?

Q5. What happens to the volume of an ideal gas if its temperature is doubled at constant pressure?

Q6. During vaporization, what does the supplied heat primarily do to the liquid?

Q7. A silver rod of length \( 1 \, \text{m} \) at \( 10^\circ \text{C} \) is heated to \( 110^\circ \text{C} \). If its cross-sectional area increases by \( 0.0076 \, \text{cm}^2 \), what was its original area? (\( \alpha_l = 1.9 \times 10^{-5} \, \text{K}^{-1} \))

Q9. Why do blacksmiths heat an iron ring before fitting it onto a wooden wheel?

Q10. What is the Celsius temperature equivalent to \( 400 \, \text{K} \)?