Question

Match List-I (Isothermal Process) with List-II (work done)

• A. $4, 3, 2, 1$
• B. $2, 1, 3, 4$
• C. $1, 2, 3, 4$
• D. $3, 4, 1, 2$

Hint:

Work done by the system is negative. Work during irreversible processes depends on external pressure $P_{\text{ext}}$, while reversible work depends on internal pressure (via integration).

Answer 1

The Correct Option is B

(P) $\text{Reversible expansion}$: $w = -n R T \ln (\frac{V_2}{V_1})$. $\rightarrow$ (2).
(Q) $\text{Free expansion}$: Expansion into vacuum, $P_{\text{ext}}=0$. $w=0$. $\rightarrow$ (1).
(R) $\text{Irreversible expansion}$: $w = -P_{\text{ext}} (V_{\text{final}} - V_{\text{initial}}) = -P_{\text{ext}} (V_2 - V_1)$. $\rightarrow$ (3).
(S) $\text{Irreversible Compression}$: $V_{\text{final}} = V_1, V_{\text{initial}} = V_2$. $w = -P_{\text{ext}} (V_1 - V_2)$. $\rightarrow$ (4).
The correct match is P-2, Q-1, R-3, S-4.