What are the simplest ions of hydrogen?

Show their reaction with water.

Probably you mean H + ion. It cannot exist as such in an aqueous liquid phase, because it is a very strong Lewis acid (electron lone pair acceptor), owing to the fact that its 1s orbital is empty. So, in the presence of water, it accepts a lone pair from the oxygen atom of H2O, thus forming a dative bond and producing an H3O + ion, known as hydroxonium ion or hydronium ion. This is the ordinary form under which H + ion is present in water and aqueous solutions.