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

The correct option is A $15L$ of $H_2$ gas at STP

22.4 L of any gas at STP = $6.02\times {10}^{23}$ molecule
$\therefore 15L$ of $H_2=\frac{6.023\times {10}^{23}}{22.4}\times 15=4.03\times {10}^{23}$
5 L of $N_2=\frac{6.023\times {10}^{23}}{22.4}\times 5=1.344\times {10}^{23}$
2 g of $H_2=6.02\times {10}^{23}$ molecules
$\therefore 0.5g$ of $H_2=\frac{6.02\times {10}^{23}}{2}\times 0.5=1.505\times {10}^{23}$
32 g of $O_2=6.02\times {10}^{23}$ molecule
10 g of $O_2=\frac{6.02\times {10}^{23}}{32}\times 10=1.88\times {10}^{23}$ molecules