Match List-I (Complex/ion) with List-II (Shape/geometry): List-I (a) $[\mathrm{PtCl}{}_2(\mathrm{NH}{}_3){}_2]$ (b) $[\mathrm{Co}(\mathrm{NH}{}_3){}_6]\mathrm{Cl}{}_3$ (c) $[\mathrm{NiCl}{}_4]{}^{2-}$ (d) $[\mathrm{Fe}(\mathrm{CO}){}_5]$ List-II (i) Octahedral (ii) Trigonal bipyramidal (iii) Square planar (iv) Tetrahedral Choose the correct option:

Solution & Explanation

\textbf{Answer:} (B) (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii). \textbf{Solution:} Geometry follows from hybridisation in each case: (a) $[\mathrm{PtCl}{}_2(\mathrm{NH}{}_3){}_2]$: Pt(II), $5d^8$, strong-field $\Rightarrow$ $ds{p}^2$ $\Rightarrow$ \textbf{square planar} (iii). (b) $[\mathrm{Co}(\mathrm{NH}{}_3){}_6]{}^{3+}$: Co(III), $3d^6$, $\mathrm{NH}{}_3$ strong-field $\Rightarrow$ $d^{2}s{p}^3$ $\Rightarrow$ \textbf{octahedral} (i). (c) $[\mathrm{NiCl}{}_4]{}^{2-}$: Ni(II), $3d^8$, weak-field $\mathrm{Cl}{}^{-}$ $\Rightarrow$ $s{p}^3$ $\Rightarrow$ \textbf{tetrahedral} (iv). (d) $[\mathrm{Fe}(\mathrm{CO}){}_5]$: Fe(0), $s{p}^{3}d$ (also written $ds{p}^3$) $\Rightarrow$ \textbf{trigonal bipyramidal} (ii). Thus (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii), option (B).