The neutron was discovered by:

Correct answer: (b) Chadwick

Explanation

The neutron was discovered by James Chadwick in 1932. He bombarded beryllium with alpha particles and showed that the radiation given off was made of uncharged particles with about the same mass as a proton. He received the 1935 Nobel Prize in Physics.

• J. J. Thomson discovered the electron (1897).
• Ernest Rutherford discovered the nucleus (1911) and the proton.
• Otto Hahn and Fritz Strassmann discovered nuclear fission (1938).
• Robert Millikan measured the charge of the electron with his oil-drop experiment.