Iron reacts with oxygen to form Fe2O3. If the atomic mass of iron is 56, the mass of oxygen that reacts with 2.5 moles of iron is
60.0g
4Fe+3O2→2Fe2O3
4 mole of Fe(4×56=224g) reacts with→3 mole O2(3×32=96g)
2.5 mole of Fe(2.5×56=140g) reacts with→140224×96=60g of O2