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Assertion (A): The highest oxidation state shown by chromium in its compounds is +6. Reason (R): A chromium atom has only six electrons in its ns and (n-1)d orbitals. 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 and (R) is true

Correct answer: Both (A) and (R) are true and (R) is the correct explanation of (A)

Solution

Cr is [Ar]3d5 4s1, giving six valence electrons (five 3d + one 4s) available for bonding, which is exactly why its maximum oxidation state is +6; the reason correctly explains the assertion.

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