The possible transitions of the electrons are from 0.0 ev to 5.5 ev and from 5.5 ev to 9.0 ev.
The minimum change in energy is from 5.5 to 9.0 equal to 4.5 ev.
Then, we need to find the speed of the electron to gain a kinetic energy of 4.5 ev from the equation KE = (1/2)m*v^2
Where,
KE = 4.5 ev * 1 J / (6.242*10^18) ev = 7.2098 * 10^ - 19 J
m = mass of the electron = 9.11 * 10 ^ -31 kg
v = √ (2 * KE/m) = √[ 2*7.2098* 10 ^ -19 kg / (9.11*10^-31kg) = 1,258,107 m/s
Answer: 1,258,107 m/s