What is formed by reaction of non-metal oxide with water ?

Acid is formed by reaction of non-metal oxide with water. This can be illustrated with the help of an example:

CO₂ + H₂O → H₂CO₃

Carbon is a non-metal and thus carbon dioxide is a non-metal oxide. Thus, when a non-metal oxide (CO₂) reacts with water, an acid (carbonic acid) is formed.