Samples of four metals $A$,$B$,$C$ and $D$ were taken and added to the following solutions one by one. The results obtained have been tabulated as follows.

Metal	Iron $(II)$ sulphate	Copper $(II)$ sulphate	Zinc sulphate	Silver nitrate
$A$	No reaction	Displacement	No reaction	Displacement
$B$	Displacement	Displacement	No reaction	Displacement
$C$	No reaction	No reaction	No reaction	Displacement
$D$	No reaction	No reaction	No reaction	No reaction

Use the table above to answer the following questions about metals $A$,$B$,$C$ and $D$:
$(i)$ Which is the most reactive metal?
$(ii)$ What would you observe if $B$ is added to a solution of Copper $(II)$ sulphate?
$(iii)$ Arrange the metals $A$,$B$,$C$ and $D$ in the order of decreasing reactivity.

(B) Based on the displacement reactions:
$1$. $B$ displaces iron,copper,and silver,but not zinc. Thus,$B$ is more reactive than iron,copper,and silver,but less reactive than zinc.
$2$. $A$ displaces copper and silver,but not iron or zinc. Thus,$A$ is more reactive than copper and silver,but less reactive than iron.
$3$. $C$ displaces only silver. Thus,$C$ is more reactive than silver,but less reactive than iron,copper,and zinc.
$4$. $D$ does not displace any of the metals. Thus,$D$ is the least reactive.
$(i)$ The most reactive metal is $B$.
$(ii)$ If $B$ is added to a solution of Copper $(II)$ sulphate,$B$ will displace copper from the solution,resulting in a color change (typically the blue solution turns colorless or pale green depending on the metal salt formed).
$(iii)$ The order of decreasing reactivity is $B > A > C > D$.