OnlineCBT
Chemistry · PYQ NEET UG 2026
हिन्दीTwo moles of an ideal gas undergo free expansion from $10\text{ L}$ to $100\text{ L}$ at $300\text{ K}$. The values of $\Delta S_{\text{system}}$ and $\Delta S_{\text{surroundings}}$ are (R is universal gas constant)
Correct answer · Option 4
$\Delta S_{\text{system}} = 4.606\text{ R}$; $\Delta S_{\text{surroundings}} = 0$
Explanation
For free expansion against vacuum, $q = 0$, so $\Delta S_{\text{surroundings}} = -q/T = 0$. The system entropy change is $\Delta S_{\text{system}} = n R \ln(V_2/V_1) = 2 R \ln(100/10) = 2(2.303) R \log(10) = 4.606 R$.
