Question

The number of moles of $H_2$ present in $0.112\text{L}$ of $H_2$ gas at STP is:

• A. $5\times {10}^{-3}\text{mol}$
• B. $5\times {10}^{-2}\text{mol}$
• C. $6\times {10}^{-3}\text{mol}$
• D. $5\times {10}^{-4}\text{mol}$

Answer 1

The correct option is A $5\times {10}^{-3}\text{mol}$

At STP, $22.4\text{L}$ is occupied by 1 mole of hydrogen gas.
$0.112\text{L}$ is occupied by $\frac{1}{22.4}\times 0.112=5\times {10}^{-3}$ moles.