ratio of e/m of electron and alpha particle is

For electron :
Charge on an electron =  1.6022 x 10^-19 Coulombs
mass of an electron = 9.109 x 10^-31 g
So charge to mass raio e/m will be =  1.6022 x 10^-19 C / 9.109 x 10^-31Kg = 1.78 x 10¹¹ C/Kg

                                                                               
For alpha particle:
charge = 2 proton = 2 x 1.6022 x 10^-19 Coulombs
mass = mass of 2 protons + mass of 2 neutrons = 4 x 1.672 x 10^-27 Kg 
The charge to mass ratio e/m =2 x 1.6022 x 10^-19 C / (4 x  1.672 x 10^-27 kg = 4.8 x 10⁷ C/kg