Question

The maximum number of molecules is present in

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

Answer 1

Answer: (A)

At $STP$,
$22.4L$ of $H_2=6.023\times 10^{23}$ molecules
$15L$ of $H_2$ $=\frac{6.023\times 10^{23}\times 15}{22.4}$
$=4.033\times 10^{23}$ molecules
$5L$ of $N_2=\frac{6.023\times 10^{23}\times 5}{22.4}$
$=1.344\times 10^{23}$ molecules
$2g$ of $H_2=6.023\times 10^{23}$ molecules
$0.5g$ of $H_2=\frac{6.023\times 10^{23}\times 0.5}{2}$
$=1.505\times 10^{23}$ molecules
$32g$ of $O_2=6.023\times 10^{23}$ molecules
$10g$ of $O_2=\frac{6.023\times 10^{23}\times 10}{32}$
$=1.882\times 10^{23}$ molecules