If you have 1 mole of a substance, how many particles do you have?

• A. 1.0 x 10^23
• B. 6.02 x 10^23
• C. 6.02 x 10^24
• D. 12.0

Answer: (B)

The main idea is Avogadro’s number: one mole contains 6.02 × 10^23 elementary entities. That fixed count is what lets you go from a measurable amount to a true number of particles. So, for 1 mole of anything, you have 6.02 × 10^23 particles (whether those particles are atoms, molecules, or ions, depending on the substance). The other options don’t fit because they represent the wrong counts: 1.0 × 10^23 is far short of Avogadro’s number, 6.02 × 10^24 is roughly ten times Avogadro’s number, and 12.0 is not a particle count.