Answer:
Part A: Protonation, Protonation
Part B: An elimination, A substitution
Step-by-step explanation:
The dehydration ethanol and the condensation of ethanol all begin from the protonation of ethanol. This is because, water is a good leaving group. Thus, the protonation of the -OH moiety of the molecule is the first step in each mechanism.
The dehydration of ethanol is an elimination reaction because it involves the loss of H-O-H from the ethanol molecule while the condensation of ethanol is an substitution reaction because the -OH moiety is replaced by -OCH2CH3.