$\begin {array} {1 1} (A)\;\text{ $FeSO_4.7H_2O$ acts as a primary standard in the volumetric analysis} \\ (B)\;\text{On standing, the crystals of ferrous sulphate becomes brown} \\ (C)\;\text{On strong heating, ferrous sulphate undergoes the reaction $2FeSO_4 \rightarrow Fe_2O_3+SO_2+SO_3$} \\ (D)\;\text{Ferrous sulphate is a reducing agent} \end {array}$
