What hypothesis led to the discovery of the proton?

The finding of the photon took place by the hypothesis that when a neutral atom of hydrogen loses an electron, a positively charged particle stays there within an atom. The proton refers to a subatomic particle, signified by the symbol p+, with a positive charge and +1e elementary charge and the mass somewhat less in comparison to that of a neutron.  

It was discovered by Rutherford that the atom must exhibit a concentrated positive center charge, which comprises the majority of the mass of the atom. It was suggested by him that the nucleus comprises a constituent with a positive charge known as the proton.  

catya your not at all which answer i've seen you do this on another question!