Q140 / 160 · TS EAMCET 2022 (20 Jul Shift 1) · Physics
An amount of $700 \mathrm{~J}$ of heat is transferred to a diatomic gas allowing it to expand with the pressure held constant. The work done on the gas is
- Correct answerA$200 \mathrm{~J}$
- B$100 \mathrm{~J}$
- C$300 \mathrm{~J}$
- D$500 \mathrm{~J}$
Solution
Work done in isobaric process is given as
$$
\begin{aligned}
& \Delta \mathrm{W}=\Delta \mathrm{Q}-\Delta \mathrm{U} \\
& =\mathrm{nC}_{\mathrm{p}} \Delta \mathrm{T}-\mathrm{nC}_{\mathrm{V}} \Delta \mathrm{T} \\
& =\mathrm{nC}_{\mathrm{P}} \Delta \mathrm{T}\left(1-\frac{1}{\gamma}\right) \\
& =\Delta \mathrm{Q}\left(1-\frac{1}{\gamma}\right) \\
& =700\left(1-\frac{5}{7}\right)=200 \mathrm{~J}
\end{aligned}
$$
Hence, the correct answer is option: 'A'.