e/m ratio of a particle of charge 2 unit and mass 4 amu ?

E/m = (2×e)/(4×m) Where e is charge of 1 electron = 1.6 x 10^-19 and m is the mass 1 u (unified mass) in kg (or you can say mass of 1 neucleon ie proton or neutron) = 1.67 x 10^-27 = (2×1.6×10^-19)C/(4×1.67×10^-27)kg = 0.479 × 10^8 C/Kg ≈4.8×10^7 C/kg