Ammonia is formed by combining H2 and N2 in the following balanced equation:
3H2 + N2 = 2NH3
To solve the equation use stoichiometry using the balanced equation above. Moles will cancel to leave the answer in liters as follows:
150L H2 * 2 moles NH3 / 3 moles H2 =100L NH3
Hope it helps!