As the mass number $A$ increases,which of the following quantities related to a nucleus does not change?

Two protons are kept at a separation of $10 \ nm$. Let $F_n$ and $F_e$ be the nuclear force and the electromagnetic force between them,respectively.

Express unified atomic mass unit $(amu)$ in $kg$.

$A$ nucleus has mass number $A_1$ and volume $V_1$. Another nucleus has mass number $A_2$ and volume $V_2$. If the relation between mass numbers is $A_2 = 4 A_1$,then $\frac{V_2}{V_1} = $ . . . . . . .

In a periodic table,the average atomic mass of magnesium is given as $24.312 \; u$. This average value is based on their relative natural abundance on Earth. The three isotopes and their masses are $_{12}^{24} Mg \; (23.98504 \; u)$,$_{12}^{25} Mg \; (24.98584 \; u)$,and $_{12}^{26} Mg \; (25.98259 \; u)$. The natural abundance of $_{12}^{24} Mg$ is $78.99 \%$. Calculate the abundances of the other two isotopes.

$A$ particle having almost zero mass and exactly zero charge is