Approximately how many electrons are in one coulomb of charge?

• A. 6.25 billion
• B. 1.0 x 10^18
• C. 6.25 billion billion
• D. 6.25 trillion

Answer: (C)

This question is about how many elementary charges fit into one coulomb of charge. Each electron carries a fixed amount of charge, about 1.60 × 10^-19 coulombs. To find how many electrons make up 1 coulomb, divide the total charge by the charge per electron: 1 C ÷ 1.60 × 10^-19 C ≈ 6.24 × 10^18 electrons. That’s roughly 6.25 × 10^18, which is often described as 6.25 billion billion electrons. So the correct choice is the one that states about 6.25 billion billion. The other options are far too small—on the order of 10^9, 10^18 (without the extra factor of 10^9), or 10^12—so they don’t match the actual count.