When sulphur reacts with oxygen, the oxide formed is ___ in nature.

The correct option is C acidic
The reaction of sulphur and oxygen gives sulphur dioxide gas. The reaction involved is:

$\text{S}\text{(s)}+{\text{O}}_2\text{(g)}\to {\text{SO}}_2\text{(g)}$

When sulphur dioxide is dissolved in water, sulphurous acid is formed. It turns blue litmus paper red. The reaction involved is:

${\text{SO}}_2\text{(g)}+{\text{H}}_2\text{O}\text{(l)}\to {\text{H}}_2{\text{SO}}_3\text{(l)}$

Hence, the oxide formed is acidic in nature.