Question

An electron in the n=7 level of the hydrogen atom relaxes to a lower energy level, emitting light of 2166 nm.
What is the value of n for the level to which the electron relaxed?

Answer 1

1/wavelength = R(1/x^2 - 1/n^2)
R is the Rydberg constant. I assume you have that in your tables. Remember wavelength must be in meters. n is 7

Answer 2

jkh