Question

The increasing order of the e/m ratio for protons, neutrons,electrons and alpha particles is?

Answer 1

I think you meant the charge/mass ratio by E/M.
Electrons and protons have the same charge.(1.602×10^-19c)But protons are 1840 times heavier than electrons.E/M of any particle decreases if the mass is increased. So the E/M of electron is higher than the proton.
Alpha particle is a helium nucleus which consists two protons and two electrons. It has +2 charge and the mass of four protons. So the alpha particle has the least E/M because of its large mass.You can see that its E/M is equal to 1/2 time E/M of a proton.
Neutron has no charge. Then its E/M is 0.
If we arrange those particles in the order of increasing E/M we get,
Neutron,Alpha particles,protons and at last electrons.