This is a stoichiometry-gas law problem.
N_2+3H_2 to 2NH_3N2+3H2→2NH3
(10L)/(22.4L) = 0.446mol[N_2]10L22.4L=0.446mol[N2]
5g* (2.02g)/H_2 = 2.48mol[H_2]5g⋅2.02gH2=2.48mol[H2]
Based on stoichiometry, you can see that N_2N2 will be the limiting reactant, so let's calculate the amount at STP.
1.0atm*10.0L = n*(0.08206L*atm)/(mol*K)*273.15K = n = 0.4461.0atm⋅10.0L=n⋅0.08206L⋅atmmol⋅K⋅273.15K=n=0.446
Well, that was a waste of time, but it's nice to double check that they are the same, anyways:
0.446mol*(2NH_3)/(N_2) approx 0.892mol[NH_3] = n0.446mol⋅2NH3N2≈0.892mol[NH3]=n
1.0*V = 0.892*(0.08206L*atm)/(mol*K)*273.15K1.0⋅V=0.892⋅0.08206L⋅atmmol⋅K⋅273.15K
thereforeV approx 20. L