Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : $[\mathrm{CoCl}(\mathrm{NH}_{3})_{5}]^{2+}$ absorbs at lower wavelength of light with respect to $[\mathrm{Co}(\mathrm{NH}_{3})_{5}(\mathrm{H}_{2} \mathrm{O})]^{3+}$ Reason R : It is because the wavelength of the light absorbed depends on the oxidation state of the metal ion. In the light of the above statements, choose the correct answer from the options given below :

(C) Both A and R are true and R is the correct explanation of A .

(D) Both A and R are true and R is NOT the correct explanation of A .

JEE Main · 2023 · 11 Apr 2023 · Shift 2 · Coordination Compounds

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A :

[CoCl (NH_{3})_{5}]^{2 +}

absorbs at lower wavelength of light with respect to

[Co (NH_{3})_{5} (H_{2} O)]^{3 +}

Reason R : It is because the wavelength of the light absorbed depends on the oxidation state of the metal ion.

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

(A)A is false but R is true.✓ Correct
(B)A is true but R is false.
(C)Both A and R are true and R is the correct explanation of A .
(D)Both A and R are true and R is NOT the correct explanation of A .

Answer: (A)

Solution

Assertion A is false.

H_{2} O

is a stronger field ligand than

Cl^{-}

, and the complex

[Co (NH_{3})_{5} (H_{2} O)]^{3 +}

has

Co^{3 +}

(higher oxidation state), leading to greater crystal field splitting energy (CFSE). Therefore, it absorbs at lower wavelength (higher energy). Reason R is true: the wavelength absorbed does depend on the oxidation state, but this doesn't correctly explain the false assertion.

JEE Main · 2023 · 11 Apr 2023 · Shift 2 · Single correct option

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JEE Main · 2023 · 11 Apr 2023 · Shift 2 · Coordination Compounds

Solution

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