From cathode-ray tube experiment, it was evident that cathode rays consisting a the property of having negatively charged species and the deflection of the cathode ray even in presence of magnetic field and changed material remain changed makes the facts : (i) It is a negatively charged particle., (iii) It is a basic constituent of all atoms and (iv) It is a constituent of cathode rays all true.

o The mass of electron :9.109382×10^-31(mass/ Kg)=0.00054(mass/u)=0 (approx. Mass/u)

o The mass of neutron :1.674927×10^–27(mass/ Kg)=1.00867(mass/u)=1(approx. Mass/u)

Therefore, the mass of an electron is almost non-existent in compared with neutron so, (ii) The mass of an electron is equal to the mass of a neutron is not possible by any means.