The mass number of a nucleus is equal to the number of

In the following reaction $_{12}M{g^{24}}{ + _2}H{e^4}{ \to _{14}}S{i^X}{ + _0}{n^1},X$ is

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$

Assertion $A:$ The binding energy per nucleon is practically independent of the atomic number for nuclei of mass number in the range $30$ to $170$.

Reason $R$ : Nuclear force is short ranged.

In the light of the above statements, choose the correct answer from the options given below on

Show that the volume of nucleus is proportional to its atomic mass number. 

If the nucleus ${}_{13}^{27}Al$ has a nuclear radius of  about $3.6\,\, fm,$ then ${ }_{32}^{125} Te$ would have its radius  approximately as …….$fm$