# NEET Physics Thermodynamics Questions Solved

The molar heat capacity in a process of a diatomic gas if it does a work of $\frac{Q}{4}$ when a heat of Q is supplied to it is -

(1) $\frac{2}{5}R$

(2) $\frac{5}{2}R$

(3) $\frac{10}{3}R$

(4) $\frac{6}{7}R$

(3) $dU={C}_{V}dT=\left(\frac{5}{2}R\right)dT$ or $dT=\frac{2\left(dU\right)}{5R}$ …..(i)

From first law of thermodynamics

$dU=dQ-dW=Q-\frac{Q}{4}=\frac{3Q}{4}$.

Now molar heat capacity $C=\frac{dQ}{dT}=\frac{Q}{\frac{2\left(dU\right)}{5R}}=\frac{5RQ}{2\left(\frac{3Q}{4}\right)}=\frac{10}{3}R$.

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