In the atomic scale,the weakest force in nature is

In the equation ${ }_{13}^{27} Al + { }_2^4 He \longrightarrow { }_{15}^{30} P + X$,the correct symbol for $X$ is:

The maximum potential energy due to electrostatic repulsion between two hydrogen nuclei is nearly (radius of the nucleus $= 1.1 \ Fermi$). $\left[ \frac{1}{4 \pi \epsilon_0} = 9 \times 10^9 \ N \ m^2 \ C^{-2} \right]$ (in $MeV$)

What is the approximate percentage of the total mass of an atom that is concentrated in its nucleus (in $\%$)?

If the radius of a nucleus with mass number $125$ is $1.5 \text{ fermi}$, then the radius of a nucleus with mass number $64$ is: (in $\text{ fermi}$)

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.