Correct option is (c) 1.5 g H2 gas
As we know
1 mole of gas at STP occupies = 22.4 L Volume
and 1 mole of molecules contains = 6.022 x 1023 molecules.
(a) 15 L H2 gas at STP = \(\frac{15}{22.4}\) mol H2 = \(\frac{15}{22.4} \times 6.022\times10^{23}\) H2 molecules
(b) 5 L N2 gas at STP = \(\frac{5}{22.4}\) mol H2 = \(\frac{5}{22.4} \times 6.022\times10^{23}\) N2 molecules
(c) 1.5 g H2 gas = \(\frac{1.5}2\) mol H2 = \(\frac{1.5}2 \times 6.022\times10^{23}\) H2 molecules
(d) 5 g of O2 gas = \(\frac5{32}\) mol H2 = \(\frac5{32}\times 6.022\times10^{23}\) O2 molecules
Hence, 1.5g of H2 gas has maximum number of H2 molecules.