The ratio of specific charge of a proton and alpha particle is

2:11:21:41:1

Specific charge means  Charge/Mass ratio
Specific charge of proton = 1
Specific charge of alpha particle = 2 ( 2 protons and 2 neutrons, neutrons have same mass as protons but charge is zero)
Therefore, ratio of specific charge of protons to alpha particles = 1:2