In which of the following options, the order of arrangements does not agree with the variation of the property indicated against it? (NEET 2016) (a) Al Mg Na F (increasing ionic size)

Ionization energy is the amount of energy required to remove an electron from a neutral gaseous atom. It increases from left to right in a period due to the decrease in atomic radius. But, the ionization potential of nitrogen is more than the ionization potential of oxygen because of the half-filled stability of nitrogen. Therefore, the order of the first ionization potential is B < C < O < N .