Question

An ideal monoatomic gas is taken around the cycle $ABCD$ as shown in figure below. Work done during the cycle is

• A. $PV$
• B. $3PV$
• C. $-PV$
• D. $0$

Answer 1

The correct option is C $-PV$


Figure shows a cyclic process $ABCD$ in counter clockwise direction.
Work done during $AD$ and $BC,W_{AD}=W_{BC}=0$
Work done during process $AB,\left(W_{AB}\right)=P(2V-V)=PV$
Work done during process $CD,\left(W_{CD}\right)=2P(V-2V)=-2PV$

$\therefore$ Net work done $\left(W\right)=W_{AB}+W_{BC}+W_{CD}+W_{DA}$
$=PV-2PV=-PV$