Question

Most accurate answer will be marked as brainliest.

Answer 1

a) A is a non metal because elements plased to the extreme right are nobel metal also known as non metal....due to its completely filled valence shell electrons.
b) As we do down the group no of shells keep on adding though nuclear charge increases...due to addition of shells the valence shell electrons go away from the nucleous....thus increases the atomic radius and hence atomic size
c) element B is placed in group 1 so it has one electron in the Valence shell,so its valency is also 1