Question

An electron with a kinetic energy of 3.90 ev collides with a sodium atom.

Answer 1

The wavelength  transition line is 
Δ = hc/Δ∈
=1240 e V. nm/3.75e V - 0,0ev
=330 .nm
Another wavelength transisiton is 
Δ = hc/Δ∈
1240e V. nm/3.19e V -2.104e V
1140 .nm
Some other wavelength transition are;
590, 816, 2180, 8860.