Question

acid contain hydrogen . water too contain hydtogen but it is not an acid. give reason

Answer 1

Acids like H Cl or H2 SO4 contain Hydrogen. But when they are in water, they exist as Hydrogen ion and Chlorine ion or Sulphate ion.

The Hydrogen ion or a proton is responsible for the acidic properties.

But pure water H2O exists as H2O and doesn't decompose into Hydrogen ions. So it doesn't have acidic properties.

Truly speaking impure water decomposes into Hydrogen ions and Hydroxide ions. But hydroxide ions are basic and so cancel the effect of acidic properties of Hydrogen ions.
So water is neutral.