Respuesta :

Answer:

B) krypton

Explanation:

Electron configuration of Br: [Ar] 3d10 4s2 4p5

Since we have the bromide ion with a negative charge, Br's atom acquired an electron and therefore another electron is added to the electronic configuration .

Electron configuration of Br-: [Ar] 3d10 4s2 4p6

And now this electronic configuration coincides with that of Krypton as we see below :

Electron configuration of Kr: [Ar] 3d10 4s2 4p6