Given two statements below :

Statement I : In ${\mathrm{Cl}}_2$ molecule the covalent radius is double of the atomic radius of chlorine.

Statement II : Radius of anionic species is always greater than their parent atomic radius.

Choose the most appropriate answer from options given below 

Outermost electronic configurations of four elements $\mathrm{A},\mathrm{B},\mathrm{C},\mathrm{D}$ are given below:

(A) $3{\mathrm{s}}^2$

(B) $3{\mathrm{s}}^{2}3{\mathrm{p}}^1$

(C) $3{\mathrm{s}}^2 3{\mathrm{p}}^3$

(D) $3{\mathrm{s}}^2 3{\mathrm{p}}^4$

The correct order of first ionisation enthalpy for them is

It is observed that characteristic X-ray spectra of elements show regularity. When frequency to the power 'n' i.e. ${\mathrm{v}}^{\mathrm{n}}$ of X-rays emitted is plotted against atomic number $\mathrm{Z}$, the following graph is obtained.

The value of 'n' is

Match List - I with List - II

Choose the correct answer from the options given below: