? + 2NaBr= 2NaCl+ Br2
So NaCl is equal on both sides.
Bromine is equal on both sides.
Chlorine gas is only present in products side.
Chlorine has 2 atoms on products side.
So Chlorine will also have 2 atoms on the reactants side.
So it will be
Cl2+ 2NaBr = 2NaCl + Br2