States of Matter 1 Question 39
39. Helium atom is two times heavier than a hydrogen molecule. At $298 \mathrm{~K}$, the average kinetic energy of a helium atom is
(a) two times that of a hydrogen molecule
$(1982,1 \mathrm{M})$
(b) same as that of a hydrogen molecule
(c) four times that of a hydrogen molecule
(d) half that of a hydrogen molecule
Show Answer
Solution:
- According to kinetic theory, average kinetic energy $(E)=\frac{3}{2} k_{B} T$ where, $k_{B}$ is Boltzmann’s constant. Since, it is independent of molar mass, it will be same for $\mathrm{He}$ and $\mathrm{H}_{2}$ at a given temperature.
