In the following nuclear reaction $_{12}Mg^{24} + _{2}He^{4} \to _{14}Si^{X} + _{0}n^{1}$,the value of $X$ is:

Pick out the correct statement from the following.

Highly energetic electrons are bombarded on a target of an element containing $30$ neutrons. The ratio of the radius of the nucleus to that of a Helium nucleus is $14^{1/3}$. The atomic number of the nucleus will be

$^{22}Ne$ nucleus after absorbing energy decays into two $\alpha$-particles and an unknown nucleus. The unknown nucleus is

Two nuclei have their mass numbers in the ratio of $1: 3$. The ratio of their nuclear densities would be

The order of the size of the nucleus and the Bohr radius of an atom,respectively,are: