If the volume of a confined gas is doubled while the temperature remain constant, what change (if any) would be observed in the pressure

The gas will obey Boyles Law:

P1 V1 = P2 V2      where P1 and V1 are the original pressure and volume and P2 and V2 are the new  values.

If V2 = 2V1  (given) then:

P1 V1 = P2 *2 V1

P2 = P1 V1 / 2V1

P2 = P1 / 2

In other words the pressure is halved. (answer).

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.