Answer:
Argon {Ar}
Explanation:
The noble gas used for a condensed electron configuration is the one before the element which you are configuring.
In this case, the element (Mn) is manganese
The noble gas that is before this element is Argon which is the row above it
so your configuration would be {Ar} 3d^5 4s^2
Atomic number is 8 and atomic mass is taken as 16 amu
Frenkel defect is a defect in crystalline solids in which an atom is displaced from its lattice position to an interstitial space. This creates a vacant space at the original site and an interstitial defect at the new site within the same element. This defect does not affect the chemical properties of the compound. This defect usually occur in ionic solids with large size difference between the anion and cation.
LiCl does not exhibit Frenkel defect because the size difference between the anion and the cation of the compound is very small.
