For each of the following pairs of molecules (or reactions), indicate which will take place more rapidly. Reason the answer.

a) 1-Bromobutane or 1-iodobutane with sodium cyanide in DMSO.
b) 1-Chloro-2-methylbutane or 1-chloropentane with sodium iodide in acetane
c) 1-Chlorohexane or chlorocyclohexane with sodium iodide in ethanol/water.
d) Solvolysis of 1-bromo-2,2-dimethylpropane or 2-bromo-2-methylpropane in methanol
e) 1-Chlorobutane with sodium acetate in acetic acid or with sodium methoxide in methanol.
f) 1-Chlorobutane with sodium azide in aqueous ethanol or sodium p-toluenesulfonate in aqueous ethanol.