Which among the following oxides is the most basic?

$Be$ and $Al$ show similarities in properties due to diagonal relationship except in the property $X$ given below. What is $X$?

Statement $I :$ Acid strength increases in the order given as $HF < HCl < HBr < HI$.
Statement $II :$ As the size of the elements $F, Cl, Br, I$ increases down the group,the bond strength of $HF, HCl, HBr$ and $HI$ decreases and so the acid strength increases.
In the light of the above statements,choose the correct answer from the options given below.

The characteristics of elements $X$,$Y$ and $Z$ with atomic numbers,respectively,$33$,$53$ and $83$ are :

Which pair of elements has the same chemical properties?

Which one of the following reactions does not occur?