Question

The colour of $K_2Cr_2O_7$ changes from red orangeto lemon yellow on treatment with aqueous KOH because of

• A. reduction of Cr(VI) to Cr(III)
• B. formation of chromium hydroxide
• C. conversion of dichromate ion to chromate
• D. oxidation of potassium hydroxide to potassium peroxide

Answer 1

Answer: (C)

conversion of dichromate ion to chromate

Answer 2

$K_2Cr_2O_7+2KOH \leftrightharpoons 2K_2CrO_4+H_2O$