Answer: \(Br^-\) , It is reduced.
Explanation:
Electronic configuration of sodium:
\([Na]=1s^22s^22p^63s^1\)
Sodium atom will loose one electron to gain noble gas configuration and form sodium cation with +1 charge.
\([Na^+]=1s^22s^22p^63s^0\)
Electronic configuration of bromine:
\([Br]:35:[Ar]3d^{10}4s^24p^5\)
Bromine atom will gain one electron to gain noble gas configuration and form bromide ion with -1 charge.
\([Br^-]:36:[Ar]3d^{10}4s^24p^6\)
Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.
Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance decreases.
\(Br+e^-\rightarrow Br^-\)
