no of moles of H2 = W/G.A.Wt
                                 Â
= 8.5*10-4/2Â Â = 4.25*10-4
N2 + 3H2 ----------------> 2NH3
        3 moles of H2
react with N2 to from 2 moles of NH3
       4.25*10-4
moles of H2 react with N2 to form =2*4.25*10-4/3
                                                                            Â
= 2.83*10-4 moles of NH3
no of molecules = no of moles* 6.023*1023
                         Â
= 2.83*10-4 * 6.023*1023
                         Â
= 1.704*1020 molecules
