Question

A gas in a closed container undergoes the cycle ABCDA as shown in the figure. The net heat absorbed by the gas after it has completed 20 cycles is:

• A. +5.0 kJ
• B. -5.0 kJ
• C. +2.5 kJ
• D. -2.5 kJ

Hint:

For cyclic processes, net heat absorbed equals net work done. The work is the area enclosed by the PV diagram: \(Q_\text{net} = W_\text{cycle} \cdot \text{number of cycles}\).

Answer 1

The Correct Option is A

Step 1: Cyclic process principle.
Over one complete cycle, ΔU = 0, so net heat absorbed equals net work done: Q_cycle = W_cycle.

Step 2: Work per cycle from PV diagram.
The enclosed area represents W_cycle, approximately 0.25 kJ based on the graph.

Step 3: Total over 20 cycles.
Q_net = 20 × W_cycle = 20 × 0.25 kJ = 5.0 kJ.

Step 4: Conclusion.
The net heat absorbed after 20 cycles is +5.0 kJ.