Question

In the $P - V$ diagram, $I$ is the initial state and $F$ is the final state. The gas goes from $I$ ot $F$ by (i) IAF, (ii) IBF, (iii) ICF. The heat absorbed by the gas is

• A. the same in all three processes
• B. the same in (i) and (ii)
• C. greater in (i) than in (ii)
• D. the same in (i) and (iii)

Answer 1

Answer: (C)

Heat absorbed in a thermodynamic process is given by $\Delta Q=\Delta U+\Delta W$.
Here $\Delta U$ is same for all the three processes as it depends only on initial and final states.
But $\Delta W _{ I }=+ Ve , \Delta W _{ II }=0, \Delta W _{\text {III }}=-$ ve
$\therefore \Delta Q _{ I }>\Delta Q _{ II }$