Final answer:
To calculate the number of moles of atoms in a sample, divide the given number of atoms by Avogadro's number.
Step-by-step explanation:
The number of moles of atoms in a sample can be calculated using Avogadro's number, which is approximately 6.022 × 10²³. To calculate the number of moles, divide the given number of atoms by Avogadro's number:
A. (3.94 × 10²²) He atoms: 3.94 × 10²² / (6.022 × 10²³) = 0.0654 moles
B. (7.13 × 10²³) K atoms: 7.13 × 10²³ / (6.022 × 10²³) = 1.18 moles
C. (4.33 × 10²¹) Ca atoms: 4.33 × 10²¹ / (6.022 × 10²³) = 7.19 × 10⁻⁴ moles