In known elements,the maximum number is of

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

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 one of the following is the most electropositive element?

Bond enthalpy of $Ge-Ge$ bond is $260 \ kJ \ mol^{-1}$. The bond enthalpies of $Si-Si$ and $Sn-Sn$ bonds in $kJ \ mol^{-1}$ are respectively

Which of the following pairs has elements containing the same number of electrons in the outermost orbit?