Question
The maximum number of molecules are present in
A.
$$15\,L\,{\text{of}}\,{H_2}\,{\text{gas}}\,{\text{at}}\,STP$$
B.
$$5\,L\,{\text{of}}\,{N_2}\,{\text{gas}}\,{\text{at}}\,STP$$
C.
$$0.5\,g\,{\text{of}}\,{H_2}\,gas$$
D.
$$10\,g\,{\text{of}}\,{O_2}\,gas$$
Answer :
$$15\,L\,{\text{of}}\,{H_2}\,{\text{gas}}\,{\text{at}}\,STP$$
Solution :
$$\eqalign{
& {\text{In}}\,15\,L\,{\text{of}}\,{H_2}\,gas\,at\,STP, \cr
& {\text{the number of molecules}} \cr
& = \frac{{6.023 \times {{10}^{23}}}}{{22.4}} \times 15 \cr
& = 4.033 \times {10^{23}} \cr
& {\text{In }}5{\text{ }}L\,{\text{of }}{N_2}{\text{ gas at }}STP, \cr
& {\text{the number of molecules}} \cr
& = \frac{{6.023 \times {{10}^{23}} \times 5}}{{22.4}} \cr
& = 1.344 \times {10^{23}} \cr
& {\text{In }}0.5{\text{ }}g{\text{ of }}{H_2}{\text{ gas,}} \cr
& {\text{the number of molecules}} \cr
& = \frac{{6.023 \times {{10}^{23}} \times 0.5}}{2} \cr
& = 1.505 \times {10^{23}} \cr
& {\text{In }}10{\text{ }}g{\text{ of }}{O_2}{\text{ gas,}} \cr
& {\text{the number of molecules}} \cr
& = \frac{{6.023 \times {{10}^{23}} \times 10}}{{32}} \cr
& = 1.882 \times {10^{23}} \cr} $$
Hence, maximum number of molecules are present in $$15{\text{ }}L$$ of $${H_2}$$ at $$STP.$$