a. Name the most metallic element in second period and most non-metallic element.
b. The element with (i) largest atomic radius and (ii) smallest atomic radius in third period.
c. The element having general electronic configuration `ns^(2)np^(4)` in fourth period.

Explanation

a. Most metallic element is `Li` and most non-metallic elements is `F`.
b. `Na` has the largest atomic radius, `Cl` has the smallest atomic radius.
c. `Se(34)1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)4s^(2)3d^(10)4p^(4)` is an element in the fourth period with general electronic configuration `ns^(2)np^4`.