(a) (i) The positive charge and most of the mass of the atom is densely concentrated in extremely small region of the atom called nucleus.
(ii) The nucleus is surrounded by electrons that ’ move around the nucleus with a very high speed in circular paths called orbits.
(iii) Electrons and the nucleus are held together by electrostatic forces of attraction.
(b) i) It failed to explain the stability of atom,
(ii) It says nothing about the electronic structure of atoms.