Answer: A) noble
Explanation:
Noble gases are group 18 elements which have completely filled valence shell. thus they do not lose or gain electrons and are called as nonreactive or noble.
Electron configuration of radon is:
[tex]Rn:[Xe]4f^{14}5d^{10}6s^26p^6[/tex]
Halogens are group 17 elements and have a valency of 1 as they can gain one electron to attain stable configuration.
Group 1 elements are alkali metals which have a valency of 1 as they can lose their outermost electron to attain stable configuration.
Diatomic means the molecule contains two atoms in one molecule.
