During the preparation of Mohr's salt solution (Ferrous ammonium sulphate), which of the following acid is added to prevent hydrolysis of

Aspects

Metal

(A)

The metal which reveals a maximum number of oxidation states

(i)

Scandium

(B)

The metal although placed in 3d block is considered not as a transition element

(ii)

Copper

(C)

The metal which does not exhibit variable oxidation states

(iii)

Manganese

(D)

The metal which in +1 oxidation state in aqueous solution undergoes disproportionation

(iv)

Zinc