Source: Extra Practice
Which of the following samples contains the largest number of atoms?
Options
Option A
1.0 g of Au (s)
Option B
1.0 g of Na (s)
Option C is correct
1.0 g of Li (s)
Option D
1.0 g of Cl2 (g)
Explanation
The number of atoms is calculated by (Mass / Atomic Mass) × Avogadro's Number. Since the mass (1.0 g) is constant for all, the sample with the lowest atomic mass will have the highest number of atoms. Atomic masses are: Au ≈ 197, Na = 23, Li = 7, Cl = 35.5 (Cl2 = 71). Lithium (Li) has the smallest atomic mass, hence 1/7 moles contains more atoms than 1/197, 1/23, or 1/71.