Question

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

• A. -5J
• B. -10J
• C. -15J
• D. -20J

Answer 1

The correct option is A -5J

For cyclic process. Total work done
$=W_{AB}+W_{BC}+W_{CA}$
$\Delta V{W}_{AB}=p\Delta V=10(2-1)=10J$
and $\Delta W_{AB}=0(asV=constant)$
For first law of thermodynamics, $\Delta Q=\Delta U+\Delta W$
$\Delta U$ = 0(Process ABCA is cyclic)
$\Rightarrow \Delta Q=\Delta W_{AB}+\Delta W_{BC}+\Delta W_{CA}$
$\Rightarrow 5=10+0+\Delta W_{CA}$
$\Rightarrow \Delta W_{CA}=–5J$