Question

An ideal gas is taken through the cycle $A\to B\to C\to A$ as shown in figure. If the heat supplied to the gas in the cycle is $5J$. The work done by the gas in the process $C\to A$

• A. $-25J$
• B. $-10J$
• C. $-15J$
• D. $-20J$

Answer 1

The correct option is A $-25J$

For cyclic process $\Delta U=0$
$\text{Q}=\text{W}={\text{W}}_{\text{AB}}+{\text{W}}_{\text{BC}}+{\text{W}}_{\text{CA}}$

$W_{BC}=0$ as process is isochoric
$W_{AB}=10(5-2)=30$ i.e. Area of line $AB$ with $V$ axis
$\Rightarrow 5=30+0+{\text{W}}_{\text{CA}}$

${\text{W}}_{\text{CA}}=-25\text{J}$