how many oxygen atoms are in h₂o?

Explanation:

Step1: Analyze the chemical formula

The chemical formula of water is $H_2O$. The sub - script after an element symbol indicates the number of atoms of that element in one molecule of the compound.

Step2: Identify the number of oxygen atoms

In $H_2O$, the sub - script of $O$ is 1 (when no sub - script is written, it is assumed to be 1). So, there is 1 oxygen atom in one molecule of water.

Answer:

1