Comment on the inter-conversion of dichromate and chromate 

Explanation

Dichromate `Cr_(2)O_(7)^(2-)` is aqueous solutions is orange red chromate `Cr_(2)O_(4)^(2-)` is aqueous solutions is yellow. When an alkali is added to dichromate, it is converted to chromate. Acidification of chromate solution gives back dichromate. Both dichromate and chromate exist in equilibrium and are inter-converted by changing the pH value of the solution.
The inter-conversion of dichromate and chromate is a non-redox reaction.