To determine the answer above, assume that the gases behave as ideal and that we only need to compare the number of moles.
For letter A. there are 5 moles of H2 gas.
For letter B, convert the amount in gas to moles by dividing it by 222 g/mol. This gives an answer of 0.0225 moles
For letter C, the given amount is Avogadro's number which corresponds to 1 mole.
Thus, the answer is letter A.
