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JEE Main 20264 AprilMorning Shift
Exam
JEE Main
Year
2026
Date
4 April
Shift
Morning Shift
Subject
Chemistry
Chapter
Thermodynamics (C)

JEE Main 2026 · 4 April · Morning Shift · Chemistry · Thermodynamics (C)

Given below are two statements: Statement I: For an ideal gas, heat...

Given below are two statements:

Statement I: For an ideal gas, heat capacity at constant volume is always greater than the heat capacity at constant pressure.

Statement II: In a constant volume process, no work is produced and all the heat withdrawn goes into the chaotic motion and is reflected by a temperature increase of the ideal gas.

In the light of the above statements, choose the correct answer from the options given below

Options

  1. ABoth Statement I and Statement II are true
  2. BBoth Statement I and Statement II are false
  3. CStatement I is true but Statement II is false
  4. DStatement I is false but Statement II is true

Correct answer

D. Statement I is false but Statement II is true

Step-by-step solution

For an ideal gas, the relationship between heat capacity at constant pressure (CpC_p) and heat capacity at constant volume (CvC_v) is given by Mayer's relation:

Cp−Cv=RC_p - C_v = R

Since the universal gas constant RR is a positive value, Cp>CvC_p > C_v. Thus, Statement I is false.

In a constant volume (isochoric) process, the change in volume ΔV=0\Delta V = 0.

Work done, W=PΔV=0W = P\Delta V = 0.

According to the first law of thermodynamics:

ΔU=q+W\Delta U = q + W

Since W=0W = 0, we get ΔU=qv\Delta U = q_v.

This means that in a constant volume process, no work is produced and all the heat absorbed by the system (withdrawn from the surroundings) goes entirely into increasing the internal energy (chaotic motion of the molecules). This increase in internal energy is reflected by an increase in the temperature of the ideal gas. Thus, Statement II is true.

Therefore, Statement I is false but Statement II is true.

Answer: Statement I is false but Statement II is true
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