The $1^{\text {st }}$ ionization enthalpy for Mg is $+737 \mathrm{~kJ} / \mathrm{mol}$. The most probable estimated value of the $2^{\text {nd }}$ ionization enthalpy of Mg is $\_\_\_\_$ .

The correct set that contains all kinds (basic, acidic, amphoteric and neutral) of oxides is :

Given below are two statements :

Statement (I) : The first ionisation enthalpy of the elements Na, Mg, Cl and Ar follows the order Na > Mg > Cl > Ar.

Statement (II) : Among Ca, Al, Fe and B, the third ionisation enthalpy is very high for Ca.

In the light of the above statements, choose the correct answer from the options given below :

Consider the elements N, P, O, S, Cl and F. The number of valence electrons present in the elements with most and least metallic character from the above list is respectively.