The correct answer is Overall neutrality of atom. • Thompson Model of an atom • Thomson proposed the model of an atom to be similar to that of a Christmas pudding. • The electrons, in a sphere of positive charge, were like currants (dry fruits) in a spherical Christmas pudding. • We can also think of a watermelon, the positive charge in the atom is spread all over like the red edible part of the watermelon, while the electrons are studded in the positively charged sphere, like the seeds in the watermelon. Related Concepts: • Rutherford model of an atom • Following observations were made: • Most of the fast-moving α-particles passed straight through the gold foil. • Some of the α-particles were deflected by the foil by small angles. • Surprisingly one out of every 12000 particles appeared to rebound. • Bohr’s model of an atom • In order to overcome the objections raised against Rutherford’s model of the atom, • Neils Bohr put forward the following postulates about the model of an atom: • Only certain special orbits known as discrete orbits of electrons are allowed inside the atom. • While revolving in discrete orbits the electrons do not radiate energy.