Which of the following complex is tetrahedral in shape? (A) [Ni(CN)_4]²- (B) [Cu(NH_3)_4]²+ (C) [NiCl_4]²- (D) [Co(en)_3]³+

ChemistryCBSE Class 12 · Sample paper, session 2026-27 · 1 mark · MCQ

CBSE Class 12 Chemistry sample paper 2026-27: question 2

From the official CBSE sample question paper for 2026-27, section A, question 2, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q2 · 1 mark · MCQCoordination Compounds

Which of the following complex is tetrahedral in shape?

(A) $[N i (C N)_{4}]^{2 -}$
(B) $[C u (N H_{3})_{4}]^{2 +}$
(C) $[N i C l_{4}]^{2 -}$
(D) $[C o (e n)_{3}]^{3 +}$

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

Open one hint at a time and try again before the next.

Hint 1

Think about whether the ligand is strong field or weak field.

Hint 2

Work out whether a weak field ligand with Ni²⁺ ( $d^{8}$ ) leads to $s p^{3}$ or $d s p^{2}$ hybridisation.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

In $[N i C l_{4}]^{2 -}$ , nickel is Ni²⁺ ( $3 d^{8}$ ). Cl⁻ is a weak field ligand, so the 3d electrons do not pair and the 3d orbitals are not freed for bonding.
The metal therefore uses $s p^{3}$ hybridisation and the complex is tetrahedral and paramagnetic. For comparison, $[N i (C N)_{4}]^{2 -}$ and $[C u (N H_{3})_{4}]^{2 +}$ are square planar ( $d s p^{2}$ ), and $[C o (e n)_{3}]^{3 +}$ is octahedral.
1 mark

Answer: Option (C) $[N i C l_{4}]^{2 -}$

Where the marks are

Chooses $[N i C l_{4}]^{2 -}$ because the weak field Cl⁻ gives $s p^{3}$ hybridisation (1 mark)

Revise the chapter

Chapter: Coordination Compounds (notes, formulas, where marks are lost and every past question)

Practise this chapterBoard-style questions from Coordination Compounds, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2026-27: every question, by section.

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CBSE Class 12 Chemistry sample paper 2026-27: question 2

Hints

Step-by-step solution

Revise the chapter

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