The five successive ionization enthalpies of an element are 800, 2427, 3658, 25024 and 32824 kJ mol^–1. The number of valence electrons in the element is :

Consider the hypothetical situation where the azimuthal quantum number, $$l$$, takes values 0, 1, 2, ....., n + 1, where n is the principal quantum number. Then, the element with atomic number :

Among the statements (I – IV), the correct ones are:
(I) Be has smaller atomic radius compared to Mg.
(II) Be has higher ionization enthalpy than Al.
(III) Charge/radius ratio of Be is greater than that of Al.
(IV) Both Be and Al form mainly covalent compounds.

The strengths of 5.6 volume hydrogen peroxide (of density 1 g/mL) in terms of mass percentage and molarity (M), respectively, are: (Take molar mass of hydrogen peroxide as 34 g/mol)