In the presence of a high concentration of Cl¯ ion the bromine undergoes addition to ethylene to give 1-bromo-2chloroethane, as well as 1,2-dibromoethane. Chloride ion does not add to the C=C unless bromine is present. Provide a suitable mechanism to explain these results. Is the rate of abomination significantly affected by the presence of the Cl¯ ion?