The wavelength of light associated with with the n=2 to n=1 electron transition in the hydrogen spectrum is?

Question

1.216x10^-7 m. by what coefficient should this wavelength be multiplied to obtain the wavelength associated with the same electron transition in the Li2+ ion?
A. 1/3
B. 1/4
C. 1/7
D. 1
E. 1/9

please explain

Answer 1

A lot of light.

Answer 2

E 1/9 The energy of the transition is proportional To Z^2

Li 2+ has one electron since Z=3

So the energy would be 9 times more than hydrogen, and wavelength being inverse to energy would be 9 times shorter