Question

which si unit of length is most commonly used to indicate the radius of an atom?
a 1 millimeter (mm)
b 1 picometer (pm)
c 1 micrometer (μm)
d 1 nanometer (nm)

Explanation:

Atoms are extremely small. Picometers are used for very small - scale lengths. 1 pm = 10⁻¹² m. Millimeters (mm), micrometers (μm), and nanometers (nm) are too large for atomic - scale measurements.

Answer:

B. 1 picometer (pm)