Spontaneity; entropy and the second law — practice questions

Question 1 · difficulty L2 · understanding

Statement 1 : There is a natural asymmetry between converting work to heat and converting heat to work. Statement 2 : No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work.

• A. Statement 1 is True, Statement 2 is True; Statement 2 is a CORRECT explanation for Statement 1.
• B. Statement 1 is True, Statement 2 is True; Statement 2 is a NOT CORRECT explanation for Statement 1.
• C. Statement 1 is True, Statement 2 is False.
• D. Statement 1 is False, Statement 2 is True.

Question 2 · difficulty L2 · understanding

For an ideal gas, consider only P-V work in going from an initial state X to the final state Z. The final state Z can be reached by either of the two paths shown in the figure. Which of the following choice(s) is(are) correct? (Take $$\Delta$$S as change in entropy and W as work done)

• A. $$\Delta {S_{X \to Z}} = \Delta {S_{X \to Y}} + \Delta {S_{Y \to Z}}$$
• B. $$\Delta {W_{X \to Z}} = \Delta {W_{X \to Y}} + \Delta {W_{Y \to Z}}$$
• C. $${W_{X \to Y \to Z}} = {W_{X \to Y}}$$
• D. $$\Delta {S_{X \to Y \to Z}} = \Delta {S_{X \to Y}}$$

Question 3 · difficulty L3 · understanding

One mole of an ideal gas at $$350 \mathrm{~K}$$ is in a $$2.0 \mathrm{~L}$$ vessel of thermally conducting walls, which are in contact with the surroundings. It undergoes isothermal reversible expansion from 2.0 L to $$3.0 \mathrm{~L}$$ against a constant pressure of $$4 \mathrm{~atm}$$. The change in entropy of the surroundings ( $$\Delta \mathrm{S})$$ is ___________ $$\mathrm{J} \mathrm{K}^{-1}$$ (Nearest integer) Given: $$\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$$.

Question 4 · difficulty L3 · understanding

Ice and water are placed in a closed container at a pressure of 1 atm and temperature 273.15 K . If pressure of the system is increased 2 times, keeping temperature constant, then identify correct observation from following

• A. Liquid phase disappears completely.
• B. The amount of ice decreases.
• C. The solid phase (ice) disappears completely.
• D. Volume of system increases .

Question 5 · difficulty L3 · understanding

For irreversible expansion of an ideal gas under isothermal condition, the correct option is :

• A. $$\Delta$$U $$\ne$$ 0, $$\Delta$$S total = 0
• B. $$\Delta$$U = 0, $$\Delta$$S total = 0
• C. $$\Delta$$U $$\ne$$ 0, $$\Delta$$S total $$\ne$$ 0
• D. $$\Delta$$U = 0, $$\Delta$$S total $$\ne$$ 0