How many molecules of H_2O are present in 18.01 g (one mole) of water?

• A. 18.01 × 10^{23}
• B. 3.011 × 10^{23}
• C. 6.022 × 10^{23}
• D. 1.204 × 10^{24}

Answer: (C)

Verified step by step guidance

1. Identify the given information: the mass of water is 18.01 g, which corresponds to one mole of water molecules.
2. Recall that one mole of any substance contains Avogadro's number of particles (atoms, molecules, etc.), which is approximately \$6.022 \times 10^{23}$ particles per mole.
3. Since the problem states you have one mole of water, the number of water molecules is directly equal to Avogadro's number.
4. Write the relationship: Number of molecules = number of moles \(\times\) Avogadro's number, or \(n \times N_A\).
5. Substitute the values: \$1 \text{ mole} \times 6.022 \times 10^{23} \text{ molecules/mole} = 6.022 \times 10^{23} \text{ molecules}$.