Neutrons were discovered by
- (a)James Chadwick
- (b)Ernest Rutherford
- (c)J. J. Thomson
- (d)John Dalton
Correct — A, James Chadwick. In 1932 the British physicist James Chadwick discovered the neutron - a neutral, uncharged particle in the nucleus - by bombarding beryllium with alpha particles and detecting a penetrating, chargeless radiation. He was awarded the Nobel Prize in Physics in 1935 for this discovery.
- (b)Ernest Rutherford — Rutherford discovered the atomic nucleus and is credited with the proton, and he predicted a neutral particle - but it was his student Chadwick who actually discovered the neutron.
- (c)J. J. Thomson — Thomson discovered the electron in 1897 through his cathode-ray experiments, not the neutron.
- (d)John Dalton — Dalton proposed the early atomic theory of indivisible atoms in the 1800s, long before subatomic particles such as the neutron were known.
The three main subatomic particles were discovered by different scientists - the electron by J. J. Thomson (1897), the nucleus and the proton by Ernest Rutherford, and the neutron by James Chadwick (1932). The neutron was the last of the three to be found because it carries no charge and is hard to detect.
Match the particle to its discoverer. The neutron was discovered in 1932 and is credited to Chadwick, so any option naming an earlier scientist is wrong.
- James Chadwick discovered the neutron in 1932 and won the 1935 Nobel Prize in Physics for it.
- The neutron is electrically neutral and sits, alongside protons, in the atomic nucleus.
- J. J. Thomson discovered the electron (1897); Rutherford is credited with the proton and the nuclear model.
- The neutral, penetrating neutron is what makes nuclear fission chain reactions possible.
- Crediting Rutherford (who predicted the neutron) rather than Chadwick (who found it).
- Mixing up Thomson (electron) with the neutron.
- Assuming an early theorist like Dalton discovered subatomic particles.
NDA asks 'who discovered the neutron/electron/proton' - pair Chadwick with the neutron, Thomson with the electron, Rutherford with the proton and nucleus.
No directly related past PYQ was found.
- practice — not a real PYQ
The electron was discovered by
- (a)James Chadwick
- (b)J. J. Thomson
- (c)John Dalton
- (d)Niels Bohr
Answer(b) J. J. Thomson - through his cathode-ray tube experiments in 1897.
- practice — not a real PYQ
The neutron carries
- (a)a positive charge
- (b)a negative charge
- (c)no charge
- (d)a variable charge
Answer(c) no charge - the neutron is electrically neutral.