Q 11-12-139JEE MainJEE Main 2019 (10 Apr, Shift 2)Easy
When heat $Q$ is supplied to a diatomic gas of rigid molecules, at constant volume its temperature increases by $\Delta T$. The heat required to produce the same change in temperature, at a constant pressure is:
Answer: (B) $\dfrac75Q$
For rigid diatomic molecules $C_V = \tfrac52R$ and $C_P = \tfrac72R$. For the same $\Delta T$:
$$\frac{Q_P}{Q} = \frac{C_P}{C_V} = \frac75 \;\Rightarrow\; Q_P = \frac75Q$$
Solution by Sreeraj P, M.Sc Physics