For which of the following items is the mole an appropriate unit of measurement?

• A. Volume of a liquid in liters
• B. Length of a chemical bond
• C. Mass of a single electron
• D. Number of atoms in a sample of carbon

Answer: (D)

Verified step by step guidance

1. Understand that the mole is a unit used to count the number of particles, such as atoms, molecules, or ions, in a given sample.
2. Recognize that volume (liters) measures space occupied, length (chemical bond length) measures distance, and mass of a single electron measures mass, none of which count discrete particles directly.
3. Identify that the mole is appropriate when quantifying the number of entities, such as atoms, molecules, or ions, rather than physical dimensions or mass of individual particles.
4. Apply this understanding to the options: volume, length, and mass of a single electron are not counted in moles, but the number of atoms in a sample is naturally expressed in moles.
5. Conclude that the mole is the correct unit for the number of atoms in a sample of carbon because it directly relates to counting a large number of discrete particles.