Which of the following samples contains the greatest number of moles?

• A. 10.0 g of O_2
• B. 10.0 g of CO_2
• C. 10.0 g of N_2
• D. 10.0 g of H_2

Answer: (D)

Verified step by step guidance

1. Identify the molar mass of each substance by summing the atomic masses of its constituent atoms. For example, for O_2, calculate the molar mass as \$2 \times$ atomic mass of O (approximately 16 g/mol).
2. Calculate the molar mass for each compound: O_2, CO_2, N_2, and H_2 using their atomic masses (O = 16 g/mol, C = 12 g/mol, N = 14 g/mol, H = 1 g/mol).
3. Use the formula to find the number of moles for each sample: \(\text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}}\).
4. Plug in the given mass (10.0 g) and the molar mass for each substance to calculate the moles for each sample.
5. Compare the calculated moles for all samples; the sample with the smallest molar mass will have the greatest number of moles for the same mass.