They are the outer layer of the electron layers.
Answer:
Base on the properties the substances possess the substance change phase from gas to liquid.
Explanation:
Generally, matter can exist in three phase namely liquid , solid and gas. The scientist has a container with a substance inside.
At first the substance moves away from each other . This means the substance was first in the gas phase . Gas molecules, because of the energy they possess , it can move rapidly and randomly and most at times move away from each other . The gas molecules tends to fill the whole volume of the container and the shape of gases are indefinite.
Later the molecules move around each other. This is a property of a liquid . A substance in liquid phase have the ability to move freely but they stay together because of the force of attraction holding them together . The substance only have the ability to move around each other because the forces holding them together won't allow them to move apart.
Base on the properties the substances possess the substance change phase from gas to liquid.
Answer:
The effective nuclear charge for a valence electron in oxygen atom: 
Explanation:
Effective nuclear charge
is the net nuclear charge experienced by the electron in a given atom. It is always less than the actual charge of the nucleus [Z], due to shielding by electrons in the inner shells.
<em>It is equal to the difference between the actual nuclear charge or the atomic number (Z) and the shielding constant (s). </em>

<u>For an oxygen atom</u>-
Electron configuration: (1s²) (2s² 2p⁴)
<em>The atomic number (actual nuclear charge): </em>Z = 8
The shielding constant (s) for a valence electron can be calculated by using the Slater's rules:
⇒ s = 5 × 0.35 + 2 × 0.85 = 1.75 + 1.7 = 3.45
<u><em>Therefore, the effective nuclear charge for a valence electron in oxygen atom is:</em></u>

<u>Therefore, the effective nuclear charge for a valence electron in oxygen atom:</u> 
The new volume at standard temperature and pressure is 5.08 L.
Explanation:
As per the kinetic theory of gases, the volume occupied by gas molecules will be inversely proportional to the pressure of the gas molecules. This is termed as Boyle's law.
So, pressure∝
Thus, if two pressure and two volumes are given then,

Now, we known the values of P₁ = 8 atm, V₁ = 635 mL, P₂ = 1 atm and V₂ we have to determine. We are considering P₂ = 1 atm, because we have to determine V₂ at standard temperature and pressure. And standard pressure is 1 atm.

Thus, the new volume at standard temperature and pressure is 5.08 L.