Question

A diatomic gas, having $C_p=\frac{7}{2}R$ and $C_v=\frac{5}{2}R$ is heated at constant pressure. The ratio $dU:dQ:dW$ is -

• A. $3:7:2$
• B. $5:7:2$
• C. $5:7:3$
• D. $3:5:2$

Answer 1

The correct option is B $5:7:2$

At constant pressure $i.e.$ in Isobaric process,

$dU:dQ:dW=C_v:C_p:R$

$\Rightarrow dU:dQ:dW=\frac{5}{2}R:\frac{7}{2}R:R$

$\Rightarrow dU:dQ:dW=5:7:2$