Draw the structure of dichromate ion.

Explanation

(i) Both chromate and dichromate ions are oxo anions of chromium and they are moderately strong oxidising agents.
(ii) In both structures, chromium is in +6 oxidation state.
(iii) In an aqueous solution, chromate and dichromate ions can be inter convertible, and in an alkaline solution, chromate ion is predominant, whereas dichromate ion becomes predominant in acidic solutions.