Which of the following represents the correct order of acidic strength?

Which one is the strongest acid?

The chemistry of lithium is very similar to that of magnesium even though they are placed in different groups. Why?

Which of the following is the most electropositive element?

Considering the elements $B$,$Al$,$Mg$,and $K$,the correct order of their metallic character is:
$(a)$ $B > Al > Mg > K$
$(b)$ $Al > Mg > B > K$
$(c)$ $Mg > Al > K > B$
$(d)$ $K > Mg > Al > B$

Which of the following is a metalloid?