Acidified potassium dichromate is treated with hydrogen sulphide. In the reactiion, the oxidation number of chromium

Options

A. Increases from `+3` to `+6`
B. Decreases from `+6` to `+3`
C. Remains unchanged
D. Decreases from `+6` to `+2`

Answer

B

Explanation

Decreases from `+6` to `+3`.
`{:(K_(2)Cr_(2)O_(7)+4H_(2)SO_(4)rarrK_(2)SO_(4)+Cr_(2)(SO_(4))_(3)+4H_(2)O+3O),([H_(2)S+[O]rarrS+H_(2)O]xx3),(bar(K_(2)overset(+6)(Cr_(2))O_(7)+4H_(2)SO_(4)+3H_(2)SrarrK_(2)SO_(4)+overset(+3)Cr(SO_(4))_(3)+7H_(2)O+3S)):}`