Concept:
Alkyl halides react with alcoholic KOH mainly through the elimination reaction (E2 mechanism).
In this reaction:
• A hydrogen atom is removed from the \(\beta\)-carbon
• The halogen atom leaves from the \(\alpha\)-carbon
• A double bond is formed
Thus an alkene is produced.
Step 1: Write the reaction.
\[
CH_3CH_2Br + KOH(\text{alc}) \rightarrow CH_2=CH_2 + KBr + H_2O
\]
Step 2: Identify the product.
The elimination of HBr from ethyl bromide forms
\[
CH_2 = CH_2
\]
which is Ethene (Ethylene).
\[
\boxed{\text{Ethene}}
\]