A line in the lyman series of hydrogen has a wavelength of 122 nm. from what state did the electron originate?

Lyman series is when the electron transitions from n≥2 to n=1. So, for the Lyman series, the Rydberg formula becomes

1/λ = R (1 - 1/n²)

where λ is the wavelength and R is the Rydberg constant for hydrogen (0.010972 nm⁻¹)

1/122 = 0.010972 (1 - 1/n²)

Solving for n,

n = 1.988≈2

Thus, the electron originated from the 2nd energy level.