How many argon (Ar) atoms are present in 1.5 × 10^2 g of argon?

• A. 6.02 × 10^23 atoms
• B. 2.26 × 10^24 atoms
• C. 3.76 × 10^25 atoms
• D. 1.50 × 10^22 atoms

Answer: (B)

Verified step by step guidance

1. Identify the given information: mass of argon (Ar) is 1.5 \times 10^{2} g.
2. Find the molar mass of argon (Ar) from the periodic table, which is approximately 39.95 g/mol.
3. Calculate the number of moles of argon using the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{1.5 \times 10^{2} \text{ g}}{39.95 \text{ g/mol}}\).
4. Use Avogadro's number, \$6.02 \times 10^{23}\( atoms/mol, to convert moles of argon to number of atoms: \)\text{atoms} = \text{moles} \times 6.02 \times 10^{23}$.
5. Multiply the moles calculated in step 3 by Avogadro's number to find the total number of argon atoms present in the sample.