The metal salt $A$ is blue in colour. When salt $A$ is heated strongly over a burner,a substance $B$ present in it is eliminated and a white powder $C$ is left behind. When a few drops of a liquid $D$ are added to powder $C$,it becomes blue again.
$(a)$ Identify $A, B, C, D$.
$(b)$ Write the chemical equations involved.
$(c)$ Give an example of a salt which also shows the above property.

(A) : Hydrated copper sulphate $(CuSO_4 \cdot 5H_2O)$
$B$: Water of crystallisation $(H_2O)$
$C$: Anhydrous copper sulphate $(CuSO_4)$
$D$: Water $(H_2O)$
$(b)$ The chemical equations are:
$CuSO_4 \cdot 5H_2O (s) \xrightarrow{\text{Heat}} CuSO_4 (s) + 5H_2O (g)$
(Blue) (White)
$CuSO_4 (s) + 5H_2O (l) \rightarrow CuSO_4 \cdot 5H_2O (s)$
(White) (Blue)
$(c)$ Another salt that shows this property is Ferrous sulphate $(FeSO_4 \cdot 7H_2O)$,which is green in colour and turns white upon heating due to the loss of water of crystallisation.