The Brainliest Answer!
I)Since the weight of an electron is thousandth part of a hydrogen atom, it would mean that a single atom, especially of the heavier elements, would contain many thousand electrons. But J.J. Thomson himself found that the number of electrons in an atom cannot be greatly different from the atomic weight. 
(ii) According to this model, hydrogen can give rise to only one spectral line, contrary to the observed fact of several lines. 
(iii) This model could not explain the large angle scattering of alpha particles by thin metal foils
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Demerits ;- Thomson said that Atom is a sphere of positive charge and electron are present in atom like seeds in watermelon.overall means there is not space present within an atom. But Rutherford proved him wrong by performing alpha ray scatering He saw mostly electron are going without any deflection. It means there is space present within atom