Identify the species

The compound $\mathrm{CrO_5}$ is known as chromium peroxide.

Recall its characteristic colour

$\mathrm{CrO_5}$ is an unstable blue-coloured compound. It is formed when hydrogen peroxide reacts with acidified dichromate/chromate solution.

Behaviour in organic solvents

Since $\mathrm{CrO_5}$ is unstable in water, it is extracted into organic solvents such as amyl alcohol, ether, etc., where it shows an intense blue colour.

Evaluate options

• A: Yellow $\rightarrow$ Incorrect
• B: Orange-Red $\rightarrow$ Incorrect
• C: Green $\rightarrow$ Incorrect
• D: Blue $\rightarrow$ Correct

Final answer

A solution of $\mathrm{CrO_5}$ in amyl alcohol has blue colour.