In Alkaline solution we have chromates and in acidic solution, dichromates ? Explain.

Explanation

Both the chromate and dichromate ions exist in equilibrium and are interconvertible depending upon the pH of solution. On adding acid, more of dichromate ions are formed and on adding alkaline solution, more of chromate ions are formed. This equilibrium can be shown as below:
`underset("Dichromate ion (Yellow) ")(2CrO_4^(2-)+ 2H^+) underset("alkali")overset("acid")(iff) underset("Dichromate ion (orange) ")(Cr_2O_7^(2-) + H_2O)`