Question

An ideal gas undergoes a four step cycle as shown in the $P-V$ diagram below During this cycle, heat is absorbed by the gas in

• A. steps 1 and 2
• B. steps 1 and 3
• C. steps 1 and 4
• D. steps 2 and 4

Answer 1

Answer: (C)

steps 1 and 4

Answer 2

Given P – V diagram

For process (1)

ΔQ1 = nCPΔT

As P = constant and V increases so T will increase

So Q1 > 0

For process (2)

ΔQ2 = nCVΔT

V = constant, P↓, So T↓

For process (3), Q3 = nCPT < 0

For process (4), Q4 = nCPT

As T > 0

So Q4 > 0

The Correct answer is option (C): steps 1 and 4