Question

Is water a base or acid?

Answer 1

We need to know that an acid is any species that donates a proton whereas base is any molecule or ion which accepts a proton. Acid forms ${H^ + }$ ions when dissolved in water while base forms $O{H^ - }$ ions when dissolved in water.

Complete answer:
We need to know that when a base and an acid react together there is a formation of salt or you can say a neutral salt, thus the reaction of acid and bases is sometimes also called a neutralization reaction. For example: a reaction is carried out between hydrochloric acid and sodium hydroxide in which $HCl$ is an acid while sodium hydroxide is a base, the salt so formed is sodium chloride i.e. $NaCl$ and water as a by-product. The reaction can be represented below:
$HCl + NaOH \to NaCl + {H_2}O$
An acid usually has a pH value lower than $7$ while a base has a pH value greater than $7$. Neutral species have a pH value $7$. In case of water it is a neutral molecule as it can work both as an acid or base depending upon the reaction requirement. Thus water is neither an acid nor a base so it is a neutral species.
So the answer is water is a neutral molecule.

Note:
We need to know that the definition says that acids are molecules that can donate a hydrogen ion i.e. a proton, while bases are molecules that can accept a hydrogen ion. The hydrochloric acid in your stomach donates a proton to other molecules, helps to break up their structure, making it an acid. The sodium hydroxide in bleach can accept a hydrogen ion, making it a base.