* Water (H₂O): A water molecule contains three atoms: two hydrogen (H) atoms and one oxygen (O) atom.

* Hydrogen chloride (HCl): A hydrogen chloride molecule contains two atoms: one hydrogen (H) atom and one chlorine (Cl) atom.

The difference lies in the specific elements that make up the molecules:

* Water: Combines two hydrogen atoms with one oxygen atom.

* Hydrogen chloride: Combines one hydrogen atom with one chlorine atom.

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