Which value represents Avogadro's number?

• A. 6.02 x 10^23
• B. 6.02 x 10^20
• C. 12
• D. 1

Answer: (A)

Avogadro's number tells you how many particles are in one mole. A mole is a counting unit that lets us move between the tiny world of atoms and measurable amounts of material. The number of particles in one mole is 6.022 x 10^23, and we often use the rounded form 6.02 x 10^23 per mole. This means one mole of any substance—whether carbon atoms, water molecules, or ions—contains that many particles. For example, 1 mole of carbon-12 has 6.022 x 10^23 carbon atoms and weighs 12 grams. The other values are not counts of particles in a mole: 12 is an atomic mass unit, 1 is just a single particle, and 6.02 x 10^20 is off by a factor of 1000.