Question

Who discovered the positively charged particles called protons?
A. James Chadwick
B. Goldstein
C. Rutherford
D. None of these.

Answer 1

Hint: Try to recall that proton is the fundamental particle which carries one unit positive charge and has a mass nearly equal to that of hydrogen atom and was discovered in 1886. Now, by using this you can easily find the correct option from the given options.

Complete step by step solution:
-It is known to you that the atom as a whole is electrically neutral and the presence of negatively charged particles in it was established, therefore, it was thought that some positively charged particles must also be present in the atom.
-For this purpose Goldstein in 1886, performed discharge tube experiments in which he took a perforated cathode and a gas at low pressure was kept inside the tube before.
-On passing high voltage between the electrodes, it was found that some rays were coming from the side of anode which passed through the holes in the cathode and produced green fluorescence on the wall coated with zinc sulphide.
-These rays were called anode rays or canal rays (because they passed through holes in cathode) and these rays contain positively charged particles which were termed as protons.
Therefore, from above we can easily say that option B is the correct option to the given question.

Note:
-It should be remembered to you that anode rays are not emitted from the anode but are produced in the space between the anode and the cathode.
-Also, you should remember that the ratio charge/mass of anode rays depends upon the nature of gas inside the discharge tube.