The concept of cmmon ion effect applies to the dissociation of weak electrolytes. Their dissociation gets further suppressed in the presence of common ions furnished by a suitable electrolyte. Similarly the solubility of sparingly soluble salts in water gets suppresessed by the presence of a common ions. You are provided with an aqueous solution containing `Cu^(2+) " and " Zn^(2+)` ions.
(i) How are these ions precipitated from the solution
(ii) What is the colour of the precipiate formed ?
(iii) How does dilute HCI help in checking the precipitation of `Zn^(2+)` ions in group II?
(iv) How does `NH_(4)OH` help in promoting the precipitation of `Zn^(2+)` ions in group IV?`