Direction (Q. Nos. 19 and 20) This section contains a paragraph, each describing theory, experiments, data, etc. 2 questions related to the paragraph have been given. Each question has only one correct answer among the four given options (a), (b), (c) and (d).
When Zn(s) is added to K2Cr2O7 dissolved in HCl(aq) , the colour of the solution changes from orange to green, then to blue and over a period of time, back to green.
Colour change of the solution from green → blue → green is due to