Describe what forms after an alkyl halide undergoes an elimination reaction.

In an elimination reaction involving an alkyl halide, the primary product formed is an alkene. This type of reaction typically involves the removal of a halogen atom and a hydrogen atom from adjacent carbon atoms in the alkyl halide.

During this process, the carbon-carbon double bond is formed as a result of the departure of the leaving group (the halide) and the abstraction of a proton from a neighboring carbon atom. This is characteristic of elimination reactions, such as E2 or E1 mechanisms. The formation of an alkene from an alkyl halide is fundamental in organic chemistry, as it is a key step in various synthetic pathways and can lead to further reactions, such as hydration to form alcohols or polymerization.

The other options represent different functional groups or types of compounds that do not directly result from the elimination of an alkyl halide. Alcohols, for example, are formed through substitution reactions or from the hydration of alkenes, while aldehydes are typically produced via oxidation of alcohols or from specific synthetic routes. Polymers are large molecules formed from repeating units, not directly resulting from elimination reactions of alkyl halides. Thus, the formation of an alkene is the most accurate representation of