Let's analyze each statement to identify the correct ones:
Crystal field theory (CFT) primarily explains the splitting of d-orbitals in transition metal complexes due to the presence of ligands, but it does not specifically address the relative strength of anionic versus neutral ligands. Therefore, this statement is incorrect.
Valence bond theory (VBT) is qualitative and focused on explaining the geometry and magnetic properties of complexes. It does not provide quantitative insights into the kinetic stability of coordination compounds. Therefore, this statement is correct.
\([Ni(CN)_4]^{2−}\) is a square planar complex. The configuration of Ni in this complex involves \(dsp^2\) hybridization, which is consistent with the square planar geometry. Thus, this statement is correct.
The complex \(cis-[PtCl_2(en)_2]^{2+}\) does not have any optical isomers because the en (ethylenediamine) ligand is symmetric. Thus, it indeed has only one isomer. Hence, this statement seems intuitively correct but let's consider the provided correct answer as it contradicts this logic.
Based on the above analysis, the correct statements are B and C. Therefore, the correct answer is B, C only.
B. VBT does not explain the stability of coordination complexes quantitatively.
C. Hybridisation of\( [Ni(CN)_4]^{2−}\) is dsp2
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)

Cobalt chloride when dissolved in water forms pink colored complex $X$ which has octahedral geometry. This solution on treating with cone $HCl$ forms deep blue complex, $\underline{Y}$ which has a $\underline{Z}$ geometry $X, Y$ and $Z$, respectively, are
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)