Question

The maximum number of molecules is present in

• A. $15\, L$ of $H_2$ gas at $STP$
• B. $5\, L$ of $N_2$ gas at $STP$
• C. $0.5\, g$ of $H_2$ gas
• D. $10\, g$ of $O_2$ gas

Answer 1

Answer: (A)

$15\, L$ of $H_2$ gas at $STP$

Answer 2

At $STP$, $22.4\, L$ of $H_2 = 6.023 \times 10^{23}$ molecules $15\,L$ of $H_2$ $=\frac{6.023 \times 10^{23} \times15}{22.4}$ $=4.033 \times 10^{23}$ molecules $5\,L$ of $N_{2}=\frac{6.023 \times10^{23} \times5}{22.4}$ $=1.344\times10^{23}$ molecules $2\,g$ of $H_{2}=6.023 \times10^{23}$ molecules $0.5\,g$ of $H_{2}=\frac{6.023 \times10^{23}\times0.5}{2}$ $=1.505\times10^{23}$ molecules $32\,g$ of $O_{2}=6.023 \times 10^{23}$ molecules $10\,g$ of $O_{2}=\frac{6.023 \times 10^{23} \times10}{32}$ $=1.882 \times 10^{23}$ molecules