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Assertion (A): K2CrO4 is yellow because of a charge-transfer transition. Reason (R): The CrO4²- ion has a tetrahedral geometry. Choose the correct option.

1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is true but (R) is false.
4. (A) is false but (R) is true.

Correct answer: Both (A) and (R) are true but (R) is not the correct explanation of (A).

Solution

In CrO4²- chromium is in +6 (d0), so colour comes from O->Cr charge transfer (A true). The ion is indeed tetrahedral (R true), but the shape is not the cause of the colour, so R does not explain A.

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