Who discovered neutron?

James Chadwick 

The correct answer is option 2. James Chadwick.

James Chadwick's discovery of the neutron in 1932 was a groundbreaking achievement in the field of nuclear physics. Here's an explanation of his discovery and its significance:

1. Experimental Observations:  Chadwick conducted experiments in which he bombarded various elements with alpha particles (positively charged helium nuclei). He observed that when beryllium was bombarded with alpha particles, an unknown form of radiation was emitted.

2. Neutral Particle:  Chadwick carefully analyzed the properties of the radiation emitted from the beryllium and concluded that it consisted of neutral particles with a mass similar to that of a proton but with no electric charge. This was a significant departure from the previously known subatomic particles, which were either positively charged (protons) or negatively charged (electrons).

3. Identification as Neutrons: Based on his experimental findings and analysis, Chadwick concluded that he had discovered a new subatomic particle, which he named the "neutron" due to its neutral (no charge) nature. Neutrons are slightly more massive than protons and are found in the nucleus of atoms alongside protons.

4. Significance: The discovery of the neutron provided crucial insights into the structure of atomic nuclei and the forces that hold them together. Neutrons, along with protons, contribute to the mass of atomic nuclei and play a key role in determining the stability and properties of nuclei. Understanding the properties of neutrons has profound implications for nuclear physics, including the development of nuclear reactors, nuclear weapons, and techniques such as neutron scattering for studying the structure of materials.

In summary, James Chadwick's discovery of the neutron was a monumental achievement that expanded our understanding of the fundamental building blocks of matter and opened up new avenues for research and technological applications in nuclear physics.