# The order of reactivitiesof the following alkyl halides for a $Sn^2$ reaction is

$(a)\;RF > RCL > RBr >RI \\ (b)\;RF > RBr > RCl >RI \\ (c)\;RCl > RBr > RF >RI \\ (d)\;RI > RBr > RCl >RF$

In $R-X$ the rate of reactions follows the order.
$R -I > R-Br > R-Cl > R-F$
$I^-$ is the best leaving group among halide ions.
Hence d is the correct answer.
answered Feb 22, 2014 by