Final answer:
There are 1.20 × 10²´ hydrogen atoms in 1.00 mole of water, since there are two hydrogen atoms per water molecule and one mole contains 6.02 × 10²³ particles.
Step-by-step explanation:
The question is asking for the number of hydrogen atoms present in 1.00 mole of water (H₂O). The chemical formula of water indicates that each molecule contains two hydrogen atoms. The concept of the mole is used here to translate a count of particles (atoms, molecules, ions, etc.) to a physical quantity. One mole, by definition, is 6.02 × 10²³ particles of the substance. To determine the number of hydrogen atoms in a mole of water, you simply multiply this Avogadro's number by two since each water molecule provides two hydrogen atoms. Therefore,
- 1 mole of water molecules (H₂O) = 6.02 × 10²³ water molecules
- 2 moles of hydrogen atoms per mole of water molecules = 2 × (6.02 × 10²³) hydrogen atoms
This gives us 1.20 × 10²´ hydrogen atoms in 1 mole of water, which is choice B in the student's multiple-choice options.