Who discovered proton?

Neutrons were discovered by

Which one of the following particles in the nucleus of an atom was discovered by J. Chadwick?

The atoms, in which the number of protons is same but the number of neutrons is different, are known as –

Rutherford's alpha particle scattering experiment on thin gold foil was responsible for the discovery of

An atom with 3 protons and 4 neutrons will have a valency of :