In Aqueous solution, metal ion M_(1) reacts separately with reagents Q and R in excess to give tetrahedral and square planar complexes respectively. An aqueous solution of another metal ion M_(2) always froms tetrahedral complexes with these reagents. Aqueous solution of M_(2) on reaction with reagent S gives white precipitate which dissolves in excess of S. The reactions are summarized in the scheme given ahead M_(1), Q and R respectively are

In Aqueous solution, metal ion M_(1) reacts separately with reagents Q

1.	In Aqueous solution, metal ion M_(1) reacts separately with reagents Q and R in excess to give tetrahedral and square planar complexes respectively. An aqueous solution of another metal ion M_(2) always froms tetrahedral complexes with these reagents. Aqueous solution of M_(2) on reaction with reagent S gives white precipitate which dissolves in excess of S. The reactions are summarized in the scheme given ahead M_(1), Q and R respectively are
Answer» `Zn^(2+)` , KCN and HCl `NI^(2+)` , HCl and KCN `CD^(2+)` , KCN and HCl `Co^(2+)` , HCl and KCN Solution :Among the four available options , `Ni^(2+)` as well as `Zn^(2+)` ions have the ability to form TETRAHEDRAL as well as square planar complexes. This depends upon the availability of the reagents used `Ni^(2+)` ion on reaction with KCN (R) FORMS a square planar complex since `CN^(-)` ion is a strong field ligand. It also reacts with HCl (Q) to form a tetrahedral complex which is quite stable `Zn^(2+)` ion on the other hand forms tetrahedral complexes with both `CN^(-)` and `CL^(-)` ions because the ion has `d^(10)` configuration which is quite stable. The sequence of the reaction involved is given.