MHTCET 26 Apr 2025 Shift 2 Paper

Concept:A neutral complex is a coordination entity whose net charge is zero.Explanation:Option A has the formula $[\mathrm{Ni}(\mathrm{CN})_{4}]^{2-}$.The cyanide ligand has a $-1$ charge and the nickel ion is $+2$.So the net charge is $2-$, which is not zero.Option B is $\mathrm{Na}_{3}[\mathrm{AlF}_{6}]$, an ionic compound with sodium counter ions.It is not a neutral coordination complex.Option C has the formula $[\mathrm{Co}(\mathrm{NH}_{3})_{3}(\mathrm{NO}_{2})_{3}]$.Here, $\mathrm{NH}_{3}$ is neutral and each $\mathrm{NO}_{2}^{-}$ carries a $-1$ charge.Three nitro groups give a total charge of $-3$.The cobalt ion is $\mathrm{Co}^{3+}$, which balances the $-3$ charge.Hence, the net charge is zero, making it a neutral complex.Option D is $[\mathrm{Cu}(\mathrm{NH}_{3})_{4}]^{2+}$, which carries a $+2$ charge.So it is also not neutral.Answer:Option C: Triamminetrinitrocobalt (III)