A.

1. When an alkyl halide is heated with aq. KOH substitution takes place but when heated with alcoholic KOH Elimination takes place.
2. The side products in an elimination reaction involving an alkyl halide and alcoholic KOH are HCl which in basic medium will be present as the salt.
3. Removal of elements of water from an alcohol is also an elimination reaction, more specifically it is called dehydration, this would convert an alcohol to an alkene.
4. Elimination is a method of creating a double bond in a molecule.
5. Hydrogenation is addition of hydrogen across multiple bonds. Dehydrohalogenation is an elimination reaction wherein a H and a halogen is removed from adjacent atoms.

B.