The correct option is B 1
Steps for finding valency factor/n-factor:
1. Find the oxidation state (O.S.) of metal in reactant side.
2. Find the oxidation state of metal in product side.
3. Take the magnitude of difference of two oxidation state |O.S.Product−O.S.Reactant|×number of atom for the valency factor
(FeSO4→Fe2O3
O.S. of Fe in product side
=2x+3×(−2)=0
x=+3
O.S. of Fe in reactant side
=x−2=0
x=+2
valency factor=number of Fe atom×|O.S.Product−O.S.Reactant|
valency factor=1×|+3−2|
valency factor=1
In this reaction, ferrous ions get oxidized to ferric ions.