Mole fraction is unit of amount of constituent, divided by total amount of all constituents in a mixture. Let us consider, there are 'x' molecular fraction of Fe2+ and (0.96−x) molecular fraction of Fe3+. Using charge conservation formula, We get, x(+2)+(0.96−x)(+3)−2=0 2x−3x+2.88−2=0 x=0.88 ∴ Fraction of Fe2+=0.88 and fraction of Fe3+=0.96−0.88=0.08 Percentage of Fe2+=