JEE Main 2026 Apr 6 Shift 2, Chemistry Q11: Colour, Magnetism And Stability Of Co-ordination Compounds

JEE Main2026Apr 6, Shift 2Chemistry

Which of the following sequence of hybridisation, geometry and magnetic nature are correct for the given coordination compounds?

A. $[NiCl_{4}]^{2 -}$ — $s p^{3}$ , tetrahedral, paramagnetic

B. $[Ni(NH_{3})_{6}]^{2 +}$ — $s p^{3} d^{2}$ , octahedral, paramagnetic

C. $[Ni(CO)_{4}]$ — $s p^{3}$ , tetrahedral, paramagnetic

D. $[Ni(CN)_{4}]^{2 -}$ — $d s p^{2}$ , square planar, diamagnetic

Choose the correct answer from the options given below:

Solution

Statements A, B, D are standard descriptions for Ni(II) complexes (Ni $^{2 +}$ is $d^{8}$ ).

$[NiCl_{4}]^{2 -}$ : weak-field Cl $^{-}$ , tetrahedral, $s p^{3}$ , 2 unpaired electrons (paramagnetic). ✓

$[Ni(NH_{3})_{6}]^{2 +}$ : outer-orbital octahedral, $s p^{3} d^{2}$ , paramagnetic. ✓

$[Ni(CN)_{4}]^{2 -}$ : strong-field CN $^{-}$ , $d s p^{2}$ square planar, diamagnetic. ✓

$[Ni(CO)_{4}]$ : Ni is in $0$ oxidation state ( $d^{10}$ ), $s p^{3}$ tetrahedral, but diamagnetic (all electrons paired). Statement C is wrong.

Correct: A, B and D.

Concept behind this question

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