QJEEM19Ch74a5: JEE Main 2019 Chemistry - Class 12 JEEM19Ch74a5 Solution: Two complexes [Cr(H 2 O) 6 ]Cl 3  (A) and [Cr(NH 3 ) 6 ]Cl …

Question

Verified Solution • 2025–26 Session moderate

Two complexes [Cr(H₂O)₆]Cl₃ (A) and [Cr(NH₃)₆]Cl₃ (B) are violet and yellow coloured, respectively. The incorrect statement regarding them is :

A Δ0 values of (A) and (B) are calculated from the energies of violet and yellow light, respectively
B both are paramagnetic with three unpaired electrons
C both absorb energies corresponding to their complementry colors.
D Δ0 value for (A) is less than that of (B).

Accepted Answer

NH₃ is a strong field ligand.

H₂O is weak field ligand.

Let

Δ

_violet is the crystal field splitting energy of complex A and

Δ

_yellow is for complex B.

∴

Δ

_yellow >

Δ

_violet.

We know,

Δ

=

\frac{h c}{λ_{a b s o r b}}

Violet color will absorb yellow color and yellow color will absorb violet color.

∴

Δ

_yellow =

\frac{h c}{λ_{v i o l e t}}

and

Δ

_violet =

\frac{h c}{λ_{y e l l o w}}

So,

Δ

_o of A is calculated from energy of yellow light and

Δ

_o of B is calculated from energy of violet light.

QJEEM19Ch74a5: JEE Main 2019 Chemistry - Class 12 JEEM19Ch74a5 Solution: Two complexes [Cr(H 2 O) 6 ]Cl 3 &nbsp;(A) and [Cr(NH 3 ) 6 ]Cl …