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

Solution

Physics sir · 2 steps

Temperature fixes the average kinetic energy of a molecule, whatever its mass.

1. What temperature measures. In kinetic theory, the average translational kinetic energy of one molecule depends only on the absolute temperature. The mass of the molecule does not appear in it.

   E̅ₜᵣₐₙₛ = 1/2mv̅²̅ = 3/2k_B T

   Quantity	Depends on	Same for all gases at fixed T?
   Average kinetic energy	3/2k_B T, only T	Yes
   Mass	the kind of molecule	No
   Speed	vᵣₘₛ = √(3k_B T/m)	No, lighter molecules move faster
   Momentum	m vᵣₘₛ = √(3mk_B T)	No, heavier molecules carry more

2. So. At a given temperature a light H₂ molecule and a heavy O₂ molecule have the same average kinetic energy. The answer is (a).

The idea to keep. Temperature is a measure of average translational kinetic energy, 3/2k_B T per molecule. Anything that also contains the mass, like speed or momentum, changes from gas to gas.

Answer from the NTA final answer key. Solution by PrepWiser.