For a certain hypothetical one electron atom the wavelength (in $ \mathring A $ ) for the spectral lines for transition from $n = p$ to $n = 1$ are given by $\lambda  = \frac{{1500{p^2}}}{{{p^2} - 1}}$ (where $p > 1$ ), then the ionization potential of this element must be ......$V$ (Take $hc = 12420\ eV- \mathring A $ )

Given below are two statements :

$Statement$ $I$ : Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford's model.

$Statement$ $II$ : An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford's model.

In the light of the above statements, choose the most appropriate from the options given below.

Why atoms are electrical neutral ? 

When an $\alpha -$particle of mass $m$ moving with velocity $v$ bombards on a heavy nucleus of charge $Z_e$ , its distance of closest approach from the nucleus depends on $m$ as

In the following diagram, which particle has highest $e/m$ value?