The first thing you MUST do is to write the balanced equation:
3H2 + N2 ==> 2NH3 ... balanced equation
Next, we convert g H2 to mols H2 and then find mols NH3:
25.0 g H2 x 1 mol / 2 g = 12.5 mols H2
12.5 mols H2 x 2 mol NH3 / 3 mol H2 = 8.33 mols NH3
Now, to find the VOLUME, we need to know the temperature and pressure because the volume of a gas in dependent on these 2 variable. Since these values aren't given, I'll assume STP (standard temperature and pressure of 1 atm and 273K). Under these conditions 1 mol of gas = 22.4 L.
8.33 mols x 22.4 L / mol = 187 L
The answer of 184.82 has no units and does not appear to be correct. It is also reported to 5 sig. figs. which would be incorrect. You should speak to the person who gave you this question and ask for the temperature and pressure otherwise you cannot answer this problem.