Which block elements in the modern periodic table are the least electropositive?

Given below are two statements:
Statement $I$: Chlorine can easily combine with oxygen to form oxides,and the product has a tendency to explode.
Statement $II$: Chemical reactivity of an element can be determined by its reaction with oxygen and halogens.
In the light of the above statements,choose the correct answer from the options given below.

How do you determine the chemical reactivity of a compound? Provide an example.

Regarding $F^{-}$ and $Cl^{-}$,which of the following statements is/are correct?
$(i)$ $Cl^{-}$ can give up an electron more easily than $F^{-}$
$(ii)$ $Cl^{-}$ is a better reducing agent than $F^{-}$
$(iii)$ $Cl^{-}$ is smaller in size than $F^{-}$
$(iv)$ $F^{-}$ can be oxidized more readily than $Cl^{-}$

In the reaction $2Br^- + X_2 \to Br_2 + 2X^-$,what is $X_2$?

Which of the following diagrams correctly represents the trend in the acidic strength of the given oxides?