Question

An aqueous solution of \( X \) on addition of hydrogen peroxide in ice-cold conditions gives blue colour to the ethereal layer. Then, \( X \) can be:

• A. Acidified potassium chromate
• B. Alkaline potassium dichromate
• C. Acidified potassium manganate
• D. Acidified potassium permanganate

Hint:

Potassium chromate reacts with hydrogen peroxide in an acidic medium to form a blue-colored solution. This is a characteristic reaction.

Answer 1

The Correct Option is A

In acidic medium, potassium chromate (\( \text{K}_2 \text{CrO}_4 \)) reacts with hydrogen peroxide to form a blue-colored solution. This reaction is a classic test for the presence of potassium chromate in an aqueous solution, as the chromate ion \( \text{CrO}_4^{2-} \) changes to a blue color when reduced. Therefore, the correct answer is acidified potassium chromate. - Option (B): Alkaline potassium dichromate does not react to form a blue color with hydrogen peroxide.
- Option (C): Potassium manganate in acid forms a purple color due to the formation of \( \text{Mn}^{2+} \), not a blue one.
- Option (D): Acidified potassium permanganate forms a purple color in the presence of hydrogen peroxide, not a blue color. Thus, the correct answer is option (A).