The volume occupied by the nucleus is about $ . . . . . . $ times the volume of an atom.

On what factor does the intensity (brightness) of spectral lines depend?

Which of the following particles is represented by the symbol $\alpha$?

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 mass of the proton is $1840$ times that of the electron. If the potential difference applied is $V$,the kinetic energy of the proton is ............ $KeV$.

Which of the following statements regarding cathode rays is incorrect?