[خيال الثلج]

The diameter of an atom is approximately 1* 10-7 mm. What is this diameter when expressed in nanometers?

A. 1 * 10-18 nm
B. 1 * 10-15 nm
C. 1 * 10-9 nm
D. 1 * 10-1 nm

الاجابة حتكون D بس كيف طلعها ؟