When orange solution containing Cr2072- ion is treated with an alkali, a yellow solution is formed and when H+ ions are added to yellow solution, an orange solution is obtained. Explain why does this happen?

 
NEETprep Answer: When orange solution containing Cr2O72-  ion is treated with an alkali, a yellow solution of Cr2O72- is obtained. On the same way Cr2O72-H+OH-CrO42-
DischromateChromate
(orange)(yellow)
 
when H+  ions are added to yellow solution, an orange solution is obtained due to interconversion.