Hey there!
5 moles will be produced.
N₂ has a molar mass of 28.014 g/mol.
Convert 70g to mol:
70 ÷ 28.014 = 2.5
In N₂ there are 2 nitrogen atoms. In NH₃ there is 1 nitrogen atom.
So, there will be twice as many moles of NH₃ because every one molecule of N₂ will produce two molecules of NH₃.
2.5 x 2 = 5 moles
Hope this helps!