a. James Chadwick discovered neutrons in 1932. Neutrons are neutral particles and they are found in the nucleus of an atom.
b. The three steps of Rutherford’s experiment for his model of an atom are -
i. He allowed fast moving alpha particles to strike a very thin gold foil in a vacuum, he found most of the alpha particles pass straight through the gold foil without any deflection from the original path.
ii. Few alpha particles deflected through small angles and few through large angles.
iii. Few alpha particles bounce back on hitting the gold foil.
c. Isobars are the atoms of different elements having a different atomic number but a same mass number. Example- 18Ar40 , 20Ca40
d. Rutherford through his gold foil experiment concluded that the size of the nucleus is very small as compared to the size of an atom.