JEE Main · 2024 · 31 Jan 2024 · Shift 1 · Heat & Thermodynamics

The parameter that remains the same for molecules of all gases at a given temperature is :

(A)kinetic energy✓ Correct
(B)momentum
(C)mass
(D)speed

Answer: (A)

Solution

The average translational kinetic energy of a gas molecule is

\overline{K E} = \frac{f}{2} k T

, which depends only on the absolute temperature

T

(and the degrees of freedom

f

, which is the same for a given class of gas), not on the mass of the molecule. So at a given temperature, kinetic energy per molecule is the same for all ideal gases.

Momentum (

p = m v

), mass, and speed all depend on molecular mass, so they differ from gas to gas even at the same temperature.

JEE Main · 2024 · 31 Jan 2024 · Shift 1 · Single correct option

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