Question

One mole of an ideal gas is taken from state A to state B by three different processes, 
(i) ACB (ii) ADB (iii) AEB as shown in the P–V diagram. The heat absorbed by the gas is 

• A. greater in process (ii) than in (i)
• B. the least in process (ii)
• C. the same in (i) and (iii)
• D. less in (iii) than in (ii)

Hint:

In P–V diagrams, larger enclosed area means more work done.

Answer 1

The Correct Option is A

Step 1: Change in internal energy depends only on initial and final states, hence same for all paths.
Step 2: Heat absorbed Q = Δ U + W
Step 3: Work done is area under P–V curve. Path ADB encloses maximum area.
Step 4: Hence heat absorbed is maximum in process (ii).