J.R. S. answered 05/28/21
Ph.D. University Professor with 10+ years Tutoring Experience
Look at oxidation numbers.
K on the left has ox.no. of 1+
K on the right has ox.no. of 1+
Br on the left has ox.no. of 1-
Br on the right has ox.no. of zero (it has been oxidized, i.e. lost electrons)
Cl on the left has ox.no. of zero
Cl on the right has ox.no. of 1- (it has been reduced, i.e. gained electrons)
1). oxidizing agent = Cl2
2). Br is oxidized
3). Cl (Cl2) is reduced
4). reducing agent = Br