Acidified solution of potassium dichromate turns green when H2S is passed through it.

Acidified solution of potassium dichromate turns green when H₂S is passed through it.

Ans.

1. Hydrogen sulphide is a reducing agent.
2. When it is passed through an acidified solution of potassium dichromate, it reduces orange – coloured potassium dichromate to green – coloured chromium sulphide.
3. Hence, the solution turns green.