Which of the following electrons should have the highest value of ionisation energy (for the same value of the principal quantum number)?

Which of the following statements is correct regarding the first $(I)$ and second $(II)$ ionization enthalpies of sodium $(Na)$ and magnesium $(Mg)$?

What are the first ionization potentials $(eV)$ of $Be$ and $Ba$ respectively?

Given below are two statements:
Statement $I$: The second ionization enthalpy of $B$, $Al$ and $Ga$ is in the order of $B > Al > Ga$.
Statement $II$: The correct order in terms of first ionization enthalpy is $Si < Ge < Pb < Sn$.

The first ionisation energies of alkaline earth metals are higher than those of the alkali metals. This is because

Ionization energy of gaseous $Na$ atoms is $495.5 \ kJ \ mol^{-1}$. The lowest possible frequency of light that ionizes a sodium atom is $(h = 6.626 \times 10^{-34} \ J \ s, N_A = 6.022 \times 10^{23} \ mol^{-1})$.