The maximum number of molecules is present in:

The maximum number of molecules is present in:
  1. $15 \mathrm{~L}$ of $\mathrm{H}_2$ gas at STP
  2. $5 \mathrm{~L}$ of $\mathrm{N}_2$ gas at STP
  3. $0.5 \mathrm{~g}$ of $\mathrm{H}_2$ gas
  4. $10 \mathrm{~g}$ of $\mathrm{O}_2$ gas

Solution

At STP $22.4 \mathrm{~L} \mathrm{H}_2=6.023 \times 10^{23}$ molecules $\begin{aligned} 15 \mathrm{~L} \mathrm{H}_2 & =\frac{6.023 \times 10^{23} \times 15}{22.4} \\ & =4.033 \times 10^{23} \\ 5 \mathrm{~L} \mathrm{~N}_2 & =\frac{6.023 \times 10^{23} \times 5}{22.4} \\ & =1.344 \times 10^{23} \\ 0.5 \mathrm{~g} \mathrm{H}_2 & =\frac{6.023 \times 10^{23} \times 0.5}{2} \\ & =1.505 \times 10^{23} \\ 10 \mathrm{~g} \mathrm{O}_2 & =\frac{6.023 \times 10^{23} \times 10}{32} \\ & =1.882 \times 10^{23} . \end{aligned}$

Asked in: NEET 2004

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