How many atoms are present in 135 g of calcium (Ca)? (Atomic mass of Ca = 40.08 g/mol)

• A. 1.35 × 10^{22} atoms
• B. 8.12 × 10^{25} atoms
• C. 2.03 × 10^{24} atoms
• D. 3.38 × 10^{23} atoms

Answer: (C)

Verified step by step guidance

1. Identify the given information: mass of calcium (Ca) is 135 g, and the atomic mass of Ca is 40.08 g/mol.
2. Calculate the number of moles of calcium using the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{135\ \text{g}}{40.08\ \text{g/mol}}\).
3. Recall that one mole of any element 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 options provided.