The chemical standard for the quantity of a mole is based on which substance?

• A. Nitrogen-14
• B. Carbon-12
• C. Hydrogen-1
• D. Oxygen-16

Answer: (B)

Verified step by step guidance

1. Understand that the mole is a fundamental unit in chemistry used to count particles such as atoms, molecules, or ions.
2. Recall that the mole is defined based on a specific number of atoms of a particular isotope, which serves as the standard reference.
3. Identify the isotope historically used to define the mole: it is based on the number of atoms in exactly 12 grams of Carbon-12.
4. Recognize that Carbon-12 was chosen because it is a stable isotope and provides a convenient and precise standard for atomic mass measurements.
5. Conclude that the chemical standard for the quantity of a mole is based on Carbon-12, not Nitrogen-14, Hydrogen-1, or Oxygen-16.