Paper: CSIR-NET December 2019 · Subject: Physical Chemistry · Chapter: Thermodynamics · Topic: Thermodynamics – General · Marks: 2 · Difficulty: Medium
A monatomic perfect gas undergoes expansion from $\left(p_{1}, V_{1}\right)$ to $\left(p_{2}, V_{2}\right)$ under isothermal or adiabatic conditions. The pressure of the gas will fall more rapidly under adiabatic conditions because
(a)$p \propto \frac{1}{V}$
(b)$p \propto \frac{1}{V^{\frac{7}{5}}}$
(c)$p \propto \frac{1}{V^{\frac{3}{2}}}$
(d)$p \propto \frac{1}{V^{\frac{5}{3}}}$
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
Isothermal: p ∝ 1/V. Adiabatic monatomic (γ = 5/3): pV^{5/3} = const, so p ∝ 1/V^{5/3} — the pressure falls faster.