How many atoms are present in a 12.0 g sample of lithium (Li)? (Atomic mass of Li = 6.94 g/mol)

• A. 2.08 × 10^{23} atoms
• B. 1.04 × 10^{24} atoms
• C. 8.64 × 10^{22} atoms
• D. 6.02 × 10^{23} atoms

Answer: (B)

Verified step by step guidance

1. Identify the given information: mass of lithium sample = 12.0 g, atomic mass of lithium (Li) = 6.94 g/mol.
2. Calculate the number of moles of lithium in the sample using the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{12.0\ \text{g}}{6.94\ \text{g/mol}}\).
3. Recall that one mole of any substance contains Avogadro's number of atoms, which is \$6.022 \times 10^{23}$ atoms/mol.
4. Calculate the total number of atoms by multiplying the number of moles by Avogadro's number: \(\text{atoms} = \text{moles} \times 6.022 \times 10^{23}\).
5. Express the final answer in scientific notation to match the format of the given options.