Question

The maximum number of molecules is present in

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

Answer 1

Answer: (B)

In $15L$ of $H_2$ gas at $STP$,
the number of molecules $=\frac{6.023\times 10^{23}}{22.4}\times 15$
$=4.033\times 10^{23}$
In $5L$ of $N_2$ gas at $STP$,
the number of molecules $=\frac{6.023\times 10^{22-}\times 5}{22.4}$
$=1.344\times 10^{23}$
In $0.5g$ of $H_2$ gas,
the number of molecules $=\frac{6.023\times 10^{23}\times 0.5}{2}$
$=1.505\times 10^{23}$
In $10g$ of $O_2$ gas,
the number of molecules $=\frac{6.023\times 10^{23}\times 10}{32}$
$=1.882\times 10^{23}$
Hence, maximum number of molecules are present in $15L$ of $H_2$ at STP.