JEE Main 2026 — 23 January, Evening Shift — Question 64

In $\left[\mathrm{Ni}(\mathrm{CO})_{4}\right], \mathrm{Ni}^{0}: 3 \mathrm{~d}^{8} 4 \mathrm{~s}^{2}$ Hybridisation state: $\mathrm{sp}^{3}$ Unpaired electron $=0$ In $\left[\mathrm{NiCl}_{4}\right]^{2-}, \mathrm{Ni}^{2+}: 3 \mathrm{~d}^{8}$ Hybridisation state: $\mathrm{sp}^{3}$ Unpaired electron $=2$ In $\left[\mathrm{PtCl}_{4}\right]^{2-}, \mathrm{Pt}^{2+}: 5 \mathrm{~d}^{8}$ Hybridisation state: $\mathrm{dsp}^{2}$ Unpaired electron $=0$ In $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}, \mathrm{Ni}^{2+}: 3 \mathrm{~d}^{8}$ Hybridisation state: $\mathrm{dsp}^{2}$ Unpaired electron $=0$ In $\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}\right], \mathrm{Pt}^{2+}: 5 \mathrm{~d}^{8}$ Hybridisation state: $\mathrm{dsp}^{2}$ Unpaired electron $=0$