To an acidified dichromate solution, some $\mathrm{H}_{2} \mathrm{O}_{2}$ is added and shaken then\

Question

Professor PC Thomas Classes · Answer

Principle of perchromic acid test.\ $\mathrm{H}_{2} \mathrm{O}_{2}$ converts dichromate to perchromic\ acid $\mathrm{CrO}_{5}$ (blue).But perchromic acid\ decomposes to give oxygen and blue colour disappears.\