The correct statements from the following are: A. The strength of anionic ligands can be explained by crystal field…

🧠 Test Each Statement

Four claims; the correct ones make the answer set.

🗺️ Walk Each

A. "Strength of anionic ligands explained by CFT." CFT partially explains anion-cation electrostatic effects, but the empirical spectrochemical series order — where CO and CN⁻ outrank halides — is not derivable from CFT alone (it requires π-back-donation, an MO concept). So A is incorrect. ✗

B. "VBT does not give a quantitative interpretation of kinetic stability." True — this is a famous limitation of VBT. VBT predicts geometry and magnetism but is silent on rate constants and lability/inertness. ✓

C. "Hybridisation of $[\mathrm{Ni(CN)_4}]^{2-}$ is $\mathrm{dsp^2}$." Ni(II) $\mathrm{d^8}$ + strong CN⁻ → square-planar → dsp². True. ✓

D. "Number of isomers of cis-$[\mathrm{PtCl_2(en)_2}]^{2+}$ is one." Cis form of $[\mathrm{PtCl_2(en)_2}]^{2+}$ (octahedral Pt(IV)) is chiral → has Δ/Λ enantiomers → 2 isomers. So D is incorrect. ✗

Correct: B and C → option (4).

⚡ VBT Limitations Anchor

What VBT cannot do:

1. Quantitatively predict magnetic moment beyond integer unpaired counts.
2. Explain colour (no $\Delta_o$ concept).
3. Predict kinetic stability (rate of ligand exchange).
4. Account for outer-orbital vs inner-orbital exceptions cleanly.

⚠️ cis = Chiral for $\mathrm{[M(LL)_2X_2]}$

A common slip: students forget that cis-bis(en)-dichloride-type complexes are chiral. The cis form has Δ and Λ — two isomers, not one.

$\boxed{\text{Answer: (4) B, C only}}$