Question

what volume of nitrous oxide gas, N2O has the same number of atoms as 9.00 L of neon gas at the same temperature and pressure

Answer 1

it is hydogen

Answer 2

At the same T and P, the number of moles Ne and the number of moles N2O will be the same for 9.00 L of each gas. Since a mole of N2O has three times as many atoms as a mole of N2, then 1/3 x 9 will give you the number of moles of N2O with an equal number of atoms of Ne.