Assertion `:[Cr(H_(2)O)_(2)]^(-2)to[Cr(H_(2)O)_(6)]^(+2)` while converthing, colour continuoulsy changes.
Reason: CFSE is increases during change.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

B

Explanation

Oxidation stathe of Cr in `[Cr (H_(2)O)_(6)]^(2+)` is +2
Electronic configuratio of `Cr=(Ar) _(18)4S^(1)3d^(2)`
Electronic condiguration of `Cr^(2+)=(Ar)_(16)3d^(4)`
`H_(2)O` is W & F ligand
CFSE value `=[-o 4 n_(zg)+0.6 n_(eg)]Delta_(o)+nP`
`=[-0.4xx3+0.6x1]Delta_(0)+0`
`=-0.6 Delta_(0)`
Oxidation state of Cr in `[Cr(H_(2)O)_(6)]^(3+)is +3`
CFSE value of `(Cr(H_(2)O)_(6)]^(3+)=[-0.4""^(n+)2g+0.6n_(eg)]Delta_(0)+nP`
`=[-0.4xx3+0]Delta_(0)+0`
`=-1.2Delta_(0)`
CFSE does not effect colour rether `Delta_(0)` value can change colour.