As a team, discuss the following complementary experimental results as they pertain to the mechanism of electrophilic aromatic substitution. 

(a) A solution of HCl and benzene is colorless and does not conduct electricity, whereas a solution of HCl and AlCl3 and benzene is colored and does conduct electricity. 

(b) The following are ¹³C NMR chemical shifts for the species below

(c) The relative rates of chlorination of the following compounds are as shown. 

(d) When 1,3,5-trimethylbenzene is treated with fluoroethane and one equivalent of BF₃ at -80°C, an isolable solid salt with a melting point of -15°C is produced. Heating the salt results in 1-ethyl-2,4,6-trimethylbenzene.

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H Cl and C5: 186.6 ppm С3: 178.1 ppm C2 and C4: 136.9 ppm C6: 52.2 ppm H- 4)