Question

When compound X reacts with dilute sulphuric acid, it releases a gas that turns acidified potassium dichromate solution from orange to green. Which of the following could be compound X?

Options

• Lead nitrate

• Copper carbonate

• Sodium chloride

• Potassium sulphite

Answer 1

Potassium sulphite

Explanation:

Potassium sulphite reacts with dilute sulphuric acid to release sulphur dioxide. SO₂ is a reducing gas that turns acidified potassium dichromate solution from orange to green.

\[\ce{K2SO3 + H2SO4 -> SO2 ^ + H2O + K2SO4}\]