In a period, the first ionisation enthalpy of the element at extreme left and the negative electron gain enthalpy of the extreme right element, except noble gases, are respectively.

Given below are two statements :

Statement I : The number of pairs among $\left[\mathrm{Al}_2 \mathrm{O}_3, \mathrm{Cr}_2 \mathrm{O}_3\right],\left[\mathrm{Cl}_2 \mathrm{O}_7, \mathrm{Mn}_2 \mathrm{O}_7\right],\left[\mathrm{Na}_2 \mathrm{O}, \mathrm{V}_2 \mathrm{O}_3\right]$ and $\left[\mathrm{CO}, \mathrm{N}_2 \mathrm{O}\right]$ that contain oxides of same nature (acidic, basic, neutral or amphoteric) is 4 .

Statement II : Among $\mathrm{Na}_2 \mathrm{O}, \mathrm{Al}_2 \mathrm{O}_3, \mathrm{CO}$ and $\mathrm{Cl}_2 \mathrm{O}_7$, the most basic and acidic oxides are $\mathrm{Na}_2 \mathrm{O}$ and $\mathrm{Cl}_2 \mathrm{O}_7$, respectively.

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

Given below are two statements:

Statement I: The correct order of electronegativity of fluorine, oxygen and nitrogen is $\mathrm{F}>\mathrm{O}>\mathrm{N}$.

Statement II: The oxidation state of oxygen in $\mathrm{OF}_2$ is +2 and in $\mathrm{Na}_2 \mathrm{O}$ is -2 .

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

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 $\_\_\_\_$ .