What size range defines nanoparticles?

• A. 1-10 nm
• B. 1-100 nm
• C. 100-1000 nm
• D. 1000-10000 nm

Answer: (B)

Nanoparticles are defined by their size, typically in the range of about 1 to 100 nanometers in diameter. At these dimensions, materials often show unique properties due to a high surface-area-to-volume ratio and quantum effects that aren’t present in larger particles. The lower end around 1 nm helps distinguish particles from individual molecules, while the upper end near 100 nm keeps them within the nanoscale. Sizes larger than this, such as 100–1000 nm or 1000–10000 nm, fall into the micrometer range and lose many nanoscale characteristics. While 1–10 nm is still nanoscale, it doesn’t capture the full common definition, so the broader 1–100 nm range is the best answer.