When chlorine reacts with potassium bromide, chlorine displaces bromine. Cl2 + 2 KBr → Bra + 2 KCI
Explain why chlorine is more reactive than bromine.

Chlorine is more reactive than bromine because the chlorine atom has fewer shells and the electronic bonding is much stronger. The electrons are closer to the nucleus, therefore it is easier for chlorine to attract and hold electrons in its outer shell forming stronger bonds with other atoms.

(As you go down Group 7/the Halogens - they get less reactive)

- decrease the number of plants and animals living in the water.