When an oxide of a non-metal reacts with water, which of the following is formed?

The correct option is A

Acid

The explanation for the correct option (A):

• Non-metallic oxides are acidic. When a non-metal oxide dissolves in Water (${\mathrm{H}}_2\mathrm{O}$), an acid is formed.
• Example: Sulfur trioxide (${\mathrm{SO}}_3$), a non-metal oxide, dissolves in Water to produce Sulfuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$). The reaction between ${\mathrm{SO}}_3$ and ${\mathrm{H}}_2\mathrm{O}$ is:

${\mathrm{SO}}_3\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)$

Final Answer: Hence, option (A) is correct. An acid is formed when an oxide of a non-metal reacts with water.