Question

Who named negatively charged particles present in cathode rays as electrons?
A) J.J. Thompson
B) Stoney
C) Goldstein
D) None of the above

Answer 1

Hint: Firstly there is a difference between discovering and naming a particle. It is a question concerned with the pure theory part. Recall the cathode ray experiment and the discovery of subatomic particles. Also keep in mind that electrons are negatively charged and protons are positively charged particles.

Complete answer:
The experiment of cathode rays led to discovery of the first subatomic particle, the electron, whose mass was found to be 1800 times less than the mass of the lightest atom, the Hydrogen.
It was discovered by J.J. Thompson while studying the electrical discharge through gases in partially evacuated glass-tubes known as cathode ray tubes.
He was sure that the newly discovered particles were not atoms but subatomic particles. Due to its small mass and size, he named the sub-atomic particle as “corpuscle”.
However, it was named as “electrons” later after particles postulated by George Johnstone Stoney in 1874.

Thus, option B is the correct answer.

Additional information:
The experimental set up of the cathode ray tube was as follows.
The cathode ray tubes were filled with neon gas. The two electrodes of these tubes, that is, anode (+ve) and cathode (-ve), were connected to a battery. The complete set up was operated at high voltage \[(10000V)\] and low pressure (about ${10^{ - 6}}Pa$).

The observations by Thompson were as follows:
1. As soon as the circuit was complete, flow of particles was observed from cathode to anode. This stream of particles was called cathode rays.
2. To confirm the presence of cathode rays, tiny holes were made in anode and the wall of the tube behind anode was connected with phosphorescent material such as zinc sulphide. When these rays pass through holes of anode and strike the zinc sulphide coating, a bright spot is developed. This confirmed the presence of rays. These rays were named as cathode rays as they start from the cathode of the discharge tube.

Note: These are pure theoretical questions, and one should remember the history of these discoveries of electrons, protons, neutrons. Proton was discovered by E Goldstein, and neutron was discovered by Chadwick. The proton was discovered in the anode ray or canal ray experiment conducted by Goldstein.