Question

A diatomic gas with rigid molecules does $10J$ of work when expanded at constant pressure. What would be the heat energy absorbed by the gas, in this process ?

• A. $35J$
• B. $40J$
• C. $25J$
• D. $30J$

Answer 1

The correct option is A $35J$

For a diatomic gas, $C_p=\frac{7}{2}R$
Since gas undergoes isobaric process
$\Rightarrow \Delta Q=n{C}_p\Delta T$
Also, $\Delta W=nR\Delta T=10J$ (given)
$\therefore \Delta Q=n\frac{7}{2}R\Delta T=\frac{7}{2}\left(nR\Delta T\right)=35J$