In chemistry, what does a mole represent?

• A. The number of protons in an atom
• B. A fixed number of particles, specifically 6.022 × 10^{23} entities
• C. The mass of one atom of hydrogen
• D. The volume occupied by one gram of a substance

Answer: (B)

Verified step by step guidance

1. Understand that a mole is a fundamental concept in chemistry used to count particles such as atoms, molecules, or ions.
2. Recognize that a mole represents a specific, fixed number of particles, which allows chemists to relate microscopic particles to macroscopic amounts.
3. Recall that this fixed number is known as Avogadro's number, which is approximately \$6.022 \times 10^{23}$ entities.
4. Note that the mole does not refer to the number of protons in an atom, the mass of an atom, or the volume occupied by a substance, but strictly to the number of particles.
5. Therefore, the mole is best defined as a quantity containing exactly \$6.022 \times 10^{23}$ particles, providing a bridge between atomic scale and laboratory scale measurements.