Answer:
B
Explanation:
Recall the law of effusion:
Because 5 mol of oxygen was effused in 10 seconds, the rate is 0.5 mol/s.
Let the rate of oxygen be <em>r</em>₁ and the rate of hydrogen be <em>r</em>₂.
The molecular weight of oxygen gas is 32.00 g/mol and the molecular weight of hydrogen gas is 2.02 g/mol.
Substitute and solve for <em>r</em>₂:
Because there are 5 moles of hydrogen gas:
In conclusion, it will take about 2.5 seconds for the hydrogen gas to effuse.
Check: Because hydrogen gas is lighter than oxygen gas, we expect that hydrogen gas will effuse quicker than oxygen gas.
