Here's how to figure out the number of hydrogen atoms in 4H₂O:

* H₂O represents one water molecule: It contains 2 hydrogen atoms (H₂) and one oxygen atom (O).

* The coefficient "4" indicates the number of molecules: 4H₂O means you have 4 water molecules.

Calculation:

* Each water molecule has 2 hydrogen atoms.

* You have 4 water molecules.

* Total hydrogen atoms = 2 atoms/molecule * 4 molecules = 8 hydrogen atoms