Question

Does the system absorb or liberate heat when it goes around the cycle in the direction shown in the figure ?

• A. Absorbs
• B. Liberates
• C. Neither absorbs nor liberate
• D. None of the above

Answer 1

The correct option is A Absorbs

As $\Delta U$ is a state function, thus $\Delta U_{cycle}=0$

Area enclosed by the cyclic process in P-V graph gives the work done by the gas during that cycle. As according to the graph the work of expansion (a to b) is greater than that of compression (b to a).

$⟹$ Net work done $W_{cycle}>0$

Using 1st law, $Q_{cycle}=\Delta U_{cycle}+W_{cycle}$

$\therefore$ $Q_{cycle}=0+W_{cycle}$ $⟹Q_{cycle}>0$

Hence the system absorbs heat.