NEET 2025 — Chemistry solution

NEET2025Chemistry

The correct order of the wavelength of light absorbed by the following complexes is:

A. [Co(NH $_{3}$ ) $_{6}$ ] $^{3 +}$ B. [Co(CN) $_{6}$ ] $^{3 -}$

C. [Cu(H $_{2}$ O) $_{4}$ ] $^{2 +}$ D. [Ti(H $_{2}$ O) $_{6}$ ] $^{3 +}$

Choose the correct answer from the options given below:

A
B < D < A < C
B
B < A < D < C
C
C < D < A < B
D
C < A < D < B

Solution

Stronger ligand field → larger $Δ_{0}$ → higher energy absorbed → shorter wavelength absorbed. So wavelength absorbed is inversely related to crystal-field splitting.

Ligand-field strength (relevant here): CN $^{-}$ > NH $_{3}$ > H $_{2}$ O. The metal also matters (Co $^{3 +}$ has larger $Δ_{0}$ than Ti $^{3 +}$ , and Cu $^{2 +}$ as a 3d $^{9}$ tetraaqua complex absorbs at the longest wavelength).

From largest $Δ_{0}$ (shortest $λ$ ) to smallest $Δ_{0}$ (longest $λ$ ): B(CN) > A(NH $_{3}$ ) > D(H $_{2}$ O on Ti) > C(H $_{2}$ O on Cu).

$∴$ Wavelength order absorbed: B < A < D < C.

← Back to full paper

Practice more Chemistry

Concept-wise practice with instant solutions on Fundamenthol.

Start practicing →