Question

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

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

Answer 1

The correct option is A

-5 J

It is a cyclic process $(\Delta v=0)$ from $1^{st}$ law of Thermodynamics,
$\Delta Q=\Delta U+\Delta W\Rightarrow \Delta Q=\Delta W5=w_{AB}+w_{BC}+w_{CA}5=10(2-1)+0+w_{CA}\Rightarrow w_{CA}=-5J$