1. Find the molar mass of water (H₂O):

* Hydrogen (H) has a molar mass of 1.01 g/mol

* Oxygen (O) has a molar mass of 16.00 g/mol

* Molar mass of H₂O = (2 * 1.01 g/mol) + 16.00 g/mol = 18.02 g/mol

2. Calculate the number of moles of water:

* Moles = Mass / Molar Mass

* Moles = 75.0 g / 18.02 g/mol = 4.16 mol H₂O

3. Determine the number of moles of hydrogen atoms:

* Each water molecule (H₂O) contains 2 hydrogen atoms.

* Moles of hydrogen atoms = 4.16 mol H₂O * (2 mol H / 1 mol H₂O) = 8.32 mol H

4. Convert moles of hydrogen atoms to number of atoms:

* Avogadro's number tells us there are 6.022 x 10²³ atoms in one mole.

* Number of hydrogen atoms = 8.32 mol H * (6.022 x 10²³ atoms/mol) = 5.01 x 10²⁴ hydrogen atoms

Therefore, there are approximately 5.01 x 10²⁴ hydrogen atoms present in 75.0 g of H₂O.