Which group is called the buffer group of the periodic table?

Which of the following properties does not depend on periodicity?

Observe the following statements:
$I$. The physical and chemical properties of elements are periodic functions of their electronic configuration.
$II$. Electronegativity of fluorine is less than the electronegativity of chlorine.
$III$. Electropositive nature decreases from top to bottom in a group.
The correct answer is:

Which of the following statements is correct regarding the following processes?
$(i) \, Cl$ $\xrightarrow{E.A.} Cl^{-} \, \, \, \, \, (ii) \, Cl^{-}$ $\xrightarrow{I.E.} Cl \, \, \, (iii) \, \, Cl$ $\xrightarrow{I.E.} Cl^{+} \, \, \, (iv) \, \, Cl^{+}$ $\xrightarrow{I.E.} Cl^{2+}$

Match the items in List-$I$ with the items in List-$II$:

List-$I$	List-$II$
$(A)$ Rubidium	$(1)$ Germanium
$(B)$ Platinum	$(2)$ Radioactive chalcogen
$(C)$ Eka-silicon	$(3)$ $s$-block element
$(D)$ Polonium	$(4)$ Atomic number $78$

Nitrogen has positive electron gain enthalpy whereas oxygen has negative. However,oxygen has lower ionisation enthalpy than nitrogen. Explain.