The Change in Energy of a One-Electron Atom or Ion

Multiple Choice

The change in energy of a one-electron atom or ion for an electronic transition from the initial energy level n_i to the final energy level n_f is given by Which of the following species will have the longest wavelength emission line for the transition between the n_i  2 and n_f  1 levels?

A) H
B) He^
C) Li^2
D) Be^3
E) B^4