1. Convert Units:

* Line length: 2 centimeters = 20,000,000 nanometers (since 1 cm = 10,000,000 nm)

2. Divide Line Length by Wavelength:

* Number of waves = Line length / Wavelength

* Number of waves = 20,000,000 nm / 1 nm = 20,000,000

Answer: 20,000,000 waves, each 1 nanometer long, would fit along a 2-centimeter line.