Noble gas. Noble gas, any of the seven chemical elements<span> that make up Group 18 (VIIIa) of the </span>periodic table<span>. The </span>elements<span> are </span>helium<span> (</span>He<span>), </span>neon<span> (</span>Ne<span>), argon (Ar), krypton (Kr), </span>xenon<span> (</span>Xe<span>), radon (Rn), and oganesson (Og)</span>
Answer is: D. Cl (chlorine).
The ionization energy (Ei) is the minimum amount of energy required to remove the valence electron, when element lose electrons, oxidation number of element grows (oxidation process).
Barium, potassium and arsenic are metals (easily lost valence electrons), chlorine is nonmetal (easily gain electrons).
Alkaline metals (in this example, potassium) have lowest ionizations energy and easy remove valence electrons (one electron), earth alkaline metals (in this example, barium) have higher ionization energy than alkaline metals, because they have two valence electrons.
Nonmetals (in this example chlorine) are far right in the main group and they have highest ionization energy, because they have many valence electrons.
Chlorine, Cl , is located in period 3, group 17 of the periodic table, and has an atomic number equal to 17 . This tells you that a neutral chlorine atom will have a total of 17 electrons surrounding its nucleus. Now, notice that the first energy level doesn't not contain a p-subshell,
