The element with the highest value of ionization potential is

Which of the following elements has the lowest ionization potential?

The element having the greatest difference between its first and second ionization energies is:

Among $Be$, $B$, $Mg$ and $Al$, the second ionisation potential is maximum for

The third ionization energy is maximum for

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