The chromyl chloride test is used to detect chloride ions in the qualitative analysis. If any chloride salt like sodium chloride is heated with acidified potassium dichromate it produces red colour fumes of chromyl chloride. It confirms the presence of chloride ions in that salt.

${\mathrm{Cl}}^{-}+{\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7+{\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{CrO}}_2{\mathrm{Cl}}_2\stackrel{\text{ Basic medium }}{\to }\underset{\text{ yellow solution }}{{\mathrm{CrO}}_4^{2-}}+{\mathrm{Cl}}^{-}$

Chromate reacts rapidly with hydrogen peroxide to exchange two oxo ligands and become diperoxochromate(VI)

$\underset{\mathrm{yellow} \mathrm{solution}}{{\mathrm{CrO}}_4^{2-}}\underset{3. 10\% {\mathrm{H}}_2{\mathrm{O}}_2}{\overset{\begin{array}{c}1. \mathrm{Acidification}\\ 2. \mathrm{Amyl} \mathrm{alcohol}\end{array}}{\to }}\underset{\mathrm{blue} \mathrm{compound}}{{\mathrm{CrO}}_5}$

Hence, the answer is option A.