The first ionization enthalpy of Na, Mg and Si, respectively, are : 496, 737 and $$786 \mathrm{~kJ} \mathrm{~mol}^{-1}$$. The first ionization enthalpy ($$\mathrm{kJ} \,\mathrm{mol}^{-1}$$) of $$\mathrm{Al}$$ is :

In which of the following pairs, electron gain enthalpies of constituent elements are nearly the same or identical?

(A) Rb and Cs

(B) Na and K

(C) Ar and Kr

(D) I and At

Choose the correct answer from the options given below :

The incorrect statement is

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 :