The first step to solve this question is to convert the given mass of nitrogen to moles:
[tex]30gN_2\cdot\frac{1molN_2}{28g}=1.07molN_2[/tex]
Use the stoichiometric ratio to find how many moles of NH3 are produced:
[tex]1.07molN_2\cdot\frac{2molNH_3}{1molN_2}=2.14molNH_3[/tex]
Use the ideal gases law to find the volume of ammonia produced:
[tex]Pv=nRT[/tex]
Solve the equation for v and replace for the known values (since the gas is at standard temperature and pressure, T is 273K and P is 1atm). Remember that R is the ideal gas constant and has a value of 0.082atmL/molK:
[tex]\begin{gathered} v=\frac{nRT}{P} \\ v=\frac{2.14\text{mol}\cdot\frac{0.082\text{atmL}}{\text{molK}}\cdot273K}{1\text{atm}} \\ v=47.9L \end{gathered}[/tex]
47.9L of ammonia are produced.