What is chemical formula of water?

In simple terms, H2O
Water can also be called H-O-H, but you're probably better off calling it H2O.
The reason it's actually called this is due to the fact that there are 2 Hydrogens per Oxygen, that enables people to call water as di-hydrogen mono-oxide as well. But again, stick with H2O unless otherwise stated :)

H2O (Hydrogen Molecules = 2. Oxygen Molecules = 1)

The chemical formula for water is H2O. A molecule of water consists of two hydrogen atom that bond with one atom of oxygen.

H20. It is known as the "universal solvent" for its ability to dissolve many substances.
Water has hydrogen bonding and it is strongly polar.
Some reactions, for example, acid-base reactions requires water.
Notice that water is amphoteric, meaning it can be both an acid and a base.

Water/Formula
H2O.

H2O, and remember the 2 is a subscript 2. There are two hydrogen for every one oxygen

H2O is chemical formula of water

H2O
Hydroxide oxygen

H20 HOH
Hydrogen Hydroxide

Di-Hydrogen Monoxide