Calculate the wavelength, in nanometers, of the light emitted by a hydrogen atom when its electron falls from the n = 7 to the n = 4 principal energy...

Calculate the wavelength, in nanometers, of the light emitted by a hydrogen atom when its electron falls from the n = 7 to the n = 4 principal energy level.

1.38 × 1014 nm

9.18 × 10-20 nm

4.45 × 10-20 nm

2.16 × 10-6 nm

2.16 × 103 nm