Which particle is free of charge?
- Aα-particle
- BElectron
- CNeutron
- DProton
- ENone of the above/More than one of the above
Show answer and explanation
Correct answer: (c) Neutron
Explanation
The neutron carries no electric charge, so it is the particle "free of charge". James Chadwick discovered it in 1932.
The others are charged: the electron is negative (−1), the proton positive (+1), and the α-particle, a helium nucleus of 2 protons and 2 neutrons, carries +2.