Question

The elements whose oxides can turn litmus solution blue are ______.

Options

• carbon and sulphur

• sodium and carbon

• potassium and magnesium

• magnesium and sulphur

Answer 1

The elements whose oxides can turn litmus solution blue are potassium and magnesium.

Explanation:

Litmus solution turns blue in the presence of a base. Metals like potassium and magnesium react with oxygen to form metallic oxides (K₂O and MgO), which are inherently basic and dissolve in water to yield alkaline solutions. Conversely, non-metals like carbon and sulphur produce acidic oxides (CO₂ and SO₂) that would instead turn litmus paper red.