Which statement best describes a mole in chemistry?

• A. A mole is the number of protons in $12$ g of carbon.
• B. A mole is the volume occupied by any gas at room temperature and pressure.
• C. A mole is the amount of substance that contains $6.022\times {10}^{23}$ elementary entities (Avogadro’s number).
• D. A mole is the mass in grams of exactly one atom of an element.

Answer: (C)