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NEET levelSingle correct optionDifficulty 1 of 3df085

On adding aqueous sodium hydroxide to orange potassium dichromate solution, the solution turns

Agreen due to $Cr X^{3 +}$
Byellow due to $CrO X_{4} X^{2 -}$
Cblue due to $CrO X_{5}$
Dcolourless due to $Cr (OH) X_{3}$

Answer: B

Alkali removes

H X^{+}

and shifts

Cr X_{2} O X_{7} X^{2 -} + H X_{2} O ⇌ 2 CrO X_{4} X^{2 -} + 2 H X^{+}

to the right, giving yellow chromate. No change in oxidation state (+6) occurs.

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