"Electron is an essential constituent of atoms of all elements"-explain.

Explanation

The value of charge (e) and mass (m) of the electron always remain the samme irrespective of the source of their emission. In the discharge tube experiment, the e/m ratio for the negatively charged particles (electrons) constituting the cathode rays was found to be the same irrespective of the nature of the cathode or the nature of the gas taken in the discharge tube. thus it can be said that electron is the essential constituent of all atoms.