Answ
Explanation:
that is like a satelite it helps detect signals from like outer space and things
N is as electronegative as Cl is. So Cl doesnt react with O, N
It's a weak base because weak bases don't dissociate completely. If it did, then it would be a strong base.
Option 2, Br. I'll go over why all other three options are incorrect.
Option 1 - Krypton is a Noble gas, and so it doesn't need to accept electrons since it has an octet.
Option 3 and 4 - Both Calcium and Barium are alkaline earth metals, and give away electrons, since they only have 2.
-T.B.