Paragraph:
An aqueous solution of metal ion \(\mathbf{M} 1\) reacts separately with reagents \(\mathbf{Q}\) and \(\mathbf{R}\) in excess to give tetrahedral and square planar complexes, respectively. An aqueous solution of another metal ion M2 always forms tetrahedral complexes with these reagents. Aqueous solution of \(\mathbf{M} 2\) on reaction with reagent \(\mathbf{S}\) gives white precipitate which dissolves in excess of \(\mathbf{S}\). The reactions are summarized in the scheme given below:


Question:
\(\mathbf{M} 1, \mathbf{Q}\) and \(\mathbf{R}\), respectively are

1. A $\mathrm{Z}{\mathrm{n}}^{2+},\mathrm{ }\mathrm{K}\mathrm{C}\mathrm{N}\mathrm{ }\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ }\mathrm{H}\mathrm{C}\mathrm{l}$
2. B $\mathrm{N}{\mathrm{i}}^{2+},\mathrm{ }\mathrm{H}\mathrm{C}\mathrm{l}\mathrm{ }\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ }\mathrm{K}\mathrm{C}\mathrm{N}$
3. C $\mathrm{C}{\mathrm{d}}^2+,\mathrm{ }\mathrm{K}\mathrm{C}\mathrm{N}\mathrm{ }\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ }\mathrm{H}\mathrm{C}\mathrm{l}$
4. D $\mathrm{C}{\mathrm{o}}^{2+},\mathrm{ }\mathrm{H}\mathrm{C}\mathrm{l}\mathrm{ }\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ }\mathrm{K}\mathrm{C}\mathrm{N}$