Question

A comparison is made at standard temperature pressure (STP) of $0.50$mol $H_2\left(g\right)$ and $1.0$ mol $He\left(g\right)$. The two gases will:

• A. have equal average molecular kinetic energies
• B. have equal molecular speed
• C. occupy equal volumes
• D. have equal effusion rates

Answer 1

The correct option is A have equal average molecular kinetic energies

$0.5$ mole of $H_2=0.5\times 2=1.0g$

$1.0$ mole of $He=1.0\times 2=2.0g$

Average kinetic energy is given by

$K=\frac{3}{2}{K}_{B}T$ where $K_B=$ Boltzmann constant

$\Rightarrow K\propto T$

Hence $2$ gases will have equal average molecular kinetic energy at standard temperature.