O3 molecular weight =16+16+16=48g∕mol It means weight of 1mol of O3 is 48g and in 1mol of O3 we have 3 atoms of Oxygen In 48g of O3, number of atoms of oxygen =3 so in 16g of O3, number of atoms of oxygen =(3∕48)×16=1 CO molecular weight =12+16=28g∕mol It means weight of 1 mol of CO is 28g and in 1 mol of CO we have 1 atom of Oxygen so in 28g of CO, number of atoms of oxygen =1 O2 molecular weight =12+16=32g∕mol It means weight of 1 mol of O2 is 32g and in 1mol of O2 we have 2 atoms of Oxygen In 32g of O2, number of atoms of oxygen =2 so in 16g of O2, number of atoms of oxygen =(2∕32)×16=1 So answer is 1:1:1