MHTCET 20 Apr 2026 Shift 2 Paper

Concept:A neutral complex has an overall charge of zero.Explanation:Check the overall charge on each complex ion.Option D: $[\mathrm{Ni}(\mathrm{CO})_4]$CO is a neutral ligand, so its charge is $0$.Let oxidation state of Ni be $x$.$x + 4(0) = 0 \Rightarrow x = 0$Thus, the complex has zero charge, so it is neutral.Option A: $\mathrm{K}_3[\mathrm{Fe}(\mathrm{CN})_5\mathrm{NO}]$ — the complex ion is charged; the salt is neutral due to $3\mathrm{K}^+$ ions.Option B: $[\mathrm{Zn}(\mathrm{NH}_3)_4]^{2+}$ has charge $+2$.Option C: $[\mathrm{Co}(\mathrm{NH}_3)_5\mathrm{Cl}]^{2+}$ has charge $+2$.Hence, only $[\mathrm{Ni}(\mathrm{CO})_4]$ is neutral.Answer:$[\mathrm{Ni}(\mathrm{CO})_4]$ is the neutral complex.