What did Rutherford conclude regarding the atomic mass?
(i) Mass of the atom is uniformly distributed.
(ii) Nucleus of an atom is much heavier than electron.
(iii) Nearly all the mass of an atom resides at the centre of an atom.
(iv) Nucleus of an atom is lighter than the electron.
Both (ii) and (iii)
According to Rutherford experiments, a very small fraction of α-particles were deflected by 1800, indicating that all the positive charge and mass of the gold atom were concentrated in a very small volume within the atom. This proves that there is a positively charged centre in the atom called nucleus. Nearly all the mass of an atom resides in the nucleus. It is not uniformly distributed throughout the atom. This also proves that mass of nucleus is much larger than mass of electron.
Mass of atom = mass of nucleus + mass of electrons, where mass of nucleus >> mass of electron.