What is the ratio of the mass of an electron to the mass of a proton?

Rutherford's alpha-particle scattering experiment first showed that the atom has a .......

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.

Alpha particles are $...$ times heavier (approximately) than neutrons.

The nature of anode rays depends upon:

Which of the following has the same mass as that of an electron?