Elements that have atoms with stable valence electron configurations in the ground state are found in

Group 18, also known as the Noble Gasses

Explanation:

Atoms strive for full stability by gaining or losing electrons to get 8 valence electrons in their valence shell, but Group 18 already has 8 electrons in their valence shell, and are therefore already stable in their ground state.

answer

i think the answer is a) as air pressure in an area increases, the density of the gas particles in that area decreases.

hope it