3. (10 pt.) Identify the type or types of mechanism (E1, E2, SN1, SN2) most consistent with the following characteristics:
a. Halomethanes react with sodium methoxide in ethanol by this mechanism only
$SN_2$
b. Primary and secondary haloalkanes generally react with weak basic nucleophiles like cyanide by this mechanism
c. The principal substitution product obtained by solvolysis of 2-Bromo-2-methylpropane in ethanol arises by this mechanism
d. In ethanol with sodium ethoxide, 2-Bromo-2-methylpropane reacts mainly by this mechanism
e. These reaction mechanisms proceed through concerted processes.
f. Reactions proceeding by these mechanisms are stereospecific.
g. These reaction mechanisms are the ones most likely to have been involved when the products are found to have a different carbon skeleton from the reactant.
h. Unhindered primary haloalkanes react with sodium ethoxide in ethanol mainly by this mechanism
i. These reaction mechanisms involve carbocation intermediates
j. Iodoalkanes react faster than bromoalkanes in reactions that proceed by these mechanisms