Molecular weight of ammonium nitrate NH4NO3 = 14 + 4(1) + 14 + 3(16)
= 32 + 48 = 80 g
80 g of ammonium nitrate contains 48 g of oxygen
∴ 100 g of ammonium nitrate will contain = 48\over 80 × 100
= 60%
Hence, the percentage of oxygen in ammonium nitrate is 60%