Determine the Energy and n(i) for the spectral line at 121.6 nm (orange).
Given:
spectral line: 121.6 nm
n(f) = 1
Find Energy and n(i)
I assume this is for the H atom.
E = hc/wavelength
You have h,c,wavelength, solve for E.
E = 2.180E-18(1/1^2 - 1/x^2)
Solve for x.
Post your work if you get stuck.
This site will tell you the answer to check what you find.
https://en.wikipedia.org/wiki/Hydrogen_spectral_series#Lyman_series_.28n.E2.80.B2_.3D_1.29