(a). A strip of Cu dissolved in `FeCl_3`, however Cu cannot displace Fe.
(b). `[CuCl_4]^(2-)` exists but `[CuI_(4)]^(2-)` does not. Why?

Explanation

This is because `E_((Fe^(3+))/(Fe^(2+))^(ɵ))gtE_((Cu^(2+))/(Cu)^(ɵ))`
`Cu_((s))+2FeCl_(3(aq))to2FeCl_(2(aq))+2CuCl_(2(aq))`.
this method is used for making printed circuit boards `(PCB'S)` used in electronic industry.
(b). `I^(ɵ)` ion is a stronger reducing agent than `Cl^(ɵ)`ion, therefore `I^(ɵ)` ion reduces `Cu^(2+)` to `Cu^(o+)` ion. As a result `CuI_2` is converted into CuI and hence `[CuI_(4)]^(2-)` does not exist.
`2CuI_2to2CuI+I_2`