Kinetic Theory

JEE Main level, single correct, medium

157 of 168

Question 157 of 168

NN moles of diatomic gas in a cylinder is at a temperature TT. Heat is supplied to the cylinder such that the temperature remains constant but nn moles of the diatomic gas get converted into monoatomic gas. The change in the total kinetic energy of the gas is

Show answer and solution

Answer: (D) 12nRT\dfrac{1}{2}nRT

Initial kinetic energy of the system,

Ui=N52RT{U}_{i}=N\dfrac{5}{2}RT

Final kinetic energy of the system,

Uf=2n32RT+(N−n)52RT{U}_{f}=2n\dfrac{3}{2}RT+\dfrac{\left(N-n\right)5}{2}RT

⇒Uf=12nRT+52NRT\Rightarrow {U}_{f}=\dfrac{1}{2}nRT+\dfrac{5}{2}NRT

ΔU=Q=12nRT\Delta U=Q=\dfrac{1}{2}nRT.

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.

More Physics practice

JEE Main Physics practice question on Kinetic Theory (Pressure and Energy of gas), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.