Identify the compound in each of the following pairs that react at the faster rate in an SN1 reaction:
(a) Isopropyl bromide or isobutyl bromide
(b) Cyclopentyl iodide or 1-methyl cyclopentyl iodide
(c) Cyclopentyl bromide or 1-Bromo-2,2-dimethylpropane
(d) tert-Butyl chloride or tert-butyl iodide

Predict whether the following reactions are more likely to undergo elimination or substitution.
Identify the mechanism of the dominant reaction (E1 versus E2; SN1 versus SN2).

() Br NH, (b) -Br H20 () Br