The size of the nucleus is measured in

$\alpha$-particles can be detected using

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.

The minimum real charge on any particle which can exist is

Which of the following statements regarding cathode rays is incorrect?

The increasing order for the values of $e/m$ $(\text{charge/mass})$ is :