Given below are two statements : Statement I: $\left[\mathrm{CoBr}_{4}\right]^{2-}$ ion will absorb light of lower energy than $\left[\mathrm{CoCl}_{4}\right]^{2-}$ ion. Statement II : In $\left[\mathrm{CoI}_{4}\right]^{2-}$ ion, the energy separation between the two set of d-orbitals is more than $\left[\mathrm{CoCl}_{4}\right]^{2-}$ ion. In the light of the above statements, choose the correct answer from the options given below :

(B) Statement I is true but Statement II is false

(A) Both Statement I and Statement II are false

(C) Statement I is false but Statement II is true

(D) Both Statement I and Statement II are true

JEE Main · 2026 · 23 Jan 2026 · Shift 1 · Coordination Compounds

Given below are two statements :

Statement I:

[CoBr_{4}]^{2 -}

ion will absorb light of lower energy than

[CoCl_{4}]^{2 -}

ion.
Statement II : In

[CoI_{4}]^{2 -}

ion, the energy separation between the two set of d-orbitals is more than

[CoCl_{4}]^{2 -}

ion.
In the light of the above statements, choose the correct answer from the options given below :

Answer: (B)

In the spectrochemical series chloride is a stronger-field ligand than bromide, so the splitting

Δ_{t}

is larger for

[CoCl_{4}]^{2 -}

than for

[CoBr_{4}]^{2 -}

. Since the energy of the absorbed light is proportional to the splitting,

[CoBr_{4}]^{2 -}

absorbs light of lower energy, making the first statement true. Iodide is a weaker-field ligand than chloride, so the d-orbital separation in

[CoI_{4}]^{2 -}

is smaller, not larger, than in

[CoCl_{4}]^{2 -}

, making the second statement false. The first statement is true and the second is false.

JEE Main · 2026 · 23 Jan 2026 · Shift 1 · Single correct option