The yellow colour of chromates changes to orange on acidification due to formation of

Options

A. `Cr^(3^+)`
B. `Cr_2 O_3`
C. `Cr_2 O_7^(2+)`
D. `CrO_4^-`

Answer

C

Explanation

In acid medium, yellow colour of `CrO_4^(2-)` (chromate ion) changes to orange colour due to the formation
of `Cr_2O_7^(2-)` (dichromate ion), `2CrO4^(2-) + 2H^+ rarr Cr__2O_7^(2-) + H_2O`