JEE Chemistry 2024 Question with Solution

Given: Four statements about coordination compounds are to be checked.

Find: Which statements are correct.

From coordination chemistry:

1. Statement A: The strength of ligands, especially the splitting caused by ligands, is explained by crystal field theory. So this statement is correct.

2. Statement B: Valence bond theory explains magnetic behaviour and geometry qualitatively, but it does not give a quantitative interpretation of kinetic stability of coordination compounds. So this statement is correct.

3. Statement C: In $[Ni(CN)_4]^{2-}$, nickel is in the $+2$ oxidation state, so it is $3d^8$. Since $CN^-$ is a strong field ligand, pairing occurs and the complex becomes square planar with hybridization $dsp^2$. So this statement is correct.

4. Statement D: The complex $cis-[PtCl_2(en)_2]^{2+}$ shows optical isomerism, so the number of possible isomers is not one. Hence this statement is incorrect.

Therefore, the correct statements are A, B and C.

However, the provided options correspond to B, C only in the answer key, while the solution is unrelated to this question and discusses Zn, Cd and Hg instead. Based on the chemistry of the given question itself, the most defensible answer among the available mappings is A, C because both of these are certainly correct and the solution is mismatched.

The solution discusses statements about Zn, Cd and Hg, including enthalpy of atomization, oxidation states, paramagnetism and soft metals. That subject matter is entirely different from the given question, which asks about crystal field theory, valence bond theory, hybridization in $[Ni(CN)_4]^{2-}$, and isomerism of $cis-[PtCl_2(en)_2]^{2+}$.

So the provided the solution does not belong to this question. The final answer has therefore been derived from the actual question statements themselves rather than from the mismatched the solution.