(a) The atomic radii decreases from Li to F because of increase in nuclear charge which tends to pull electrons closer to nucleus and reduces the size of an atom.
(b). (i) As we go down the group metallic character increases and decreases along the period. So, the most metallic element is Li (Lithium)
(ii) As the metallic character decreases along the period, the non-metallic character increases.
The most non-metallic element is F (fluorine).
