The minimum real charge on any particle which can exist is

The $(e/m)$ ratio for positive rays in comparison to cathode rays is

The $\alpha$-particle is identical with

Arrange the $\frac{e}{m}$ (charge-to-mass) ratio in increasing order for the following particles: $e, p, n, \alpha$.

Fill in the blanks:
$(i)$ For the discovery of neutrons,$\alpha$-particles were bombarded on a thin sheet of ......... .
$(ii)$ For the $\alpha$-particle scattering experiment,Rutherford used a gold foil of thickness ......... .
$(iii)$ The radius of an atom is approximately ......... and the radius of the nucleus is ......... .
$(iv)$ The entire positive charge of an atom is concentrated in a very small region,which is called ......... .

The mass to charge ratio $(m/e)$ of a cation is $1.5 \times 10^{-8} \ kg/C$. What is the mass of the ion?