A mole of carbon-12 has a mass of which value?

• A. 6.02 g
• B. 1.00 g
• C. 24.0 g
• D. 12.000 g

Answer: (D)

A mole links a specific count of particles to a mass via molar mass. For carbon-12, by definition one mole contains Avogadro’s number of atoms and each atom has a mass of exactly 12 atomic mass units, so the molar mass is exactly 12 g per mole. Therefore, a mole of carbon-12 has a mass of 12.000 g. The other values don’t fit this relation: 6.02 g would be a misinterpretation of Avogadro’s number, 1.00 g would correspond to a very small fraction of a mole, and 24.0 g would be two moles of carbon-12.