Which of the following pairs has the identical $e/m$ value?

Fill in the blanks given below:
$(i)$ The circular path around the nucleus in which electrons revolve at high speed is called ......... .
$(ii)$ Electrons and the nucleus are held together by ......... force.
$(iii)$ The number of $P^{+}$ in the nucleus and the sum of the number of $P^{+}$ and $n^{\circ}$ in the nucleus are represented by the symbols ...... and ......... respectively.
$(iv)$ The sum of the number of $P^{+}$ and $n^{\circ}$ in the nucleus is represented by the term ...... and the symbol .... respectively.

Explain the discovery of protons.

Which of the following statements is incorrect regarding cathode rays?

Which of the following statements is not the result of the cathode ray discharge tube experiment?

The proton and neutron are collectively called as