List of top Chemistry Questions on Periodic Table and Periodicity

The most electronegative element among the following is:
Which element behaves chemically both as a metal and as a non-metal (a metalloid)?
Which element never exhibits a positive oxidation state in any of its compounds?
The high reactivity of fluorine among the halogens is mainly due to:
The ionic radii of N3-, O2-, F- and Na+ follow the order:
The most electropositive element among the following is: