Elimination reaction converts bromoethane to ethene by removing HBr

Steps:

• Bromoethane (CH₃CH₂Br) undergoes elimination with a base like alcoholic KOH.
• The reaction removes H from the β-carbon and Br from the α-carbon, forming a C=C bond.
• This yields ethene (CH₂=CH₂) as the alkene product.
• Other options result from substitution, not elimination.

Why B is correct:

• Elimination (E2 mechanism) of haloalkanes follows the general equation R-CH₂-CH₂-X → R-CH=CH₂ + HX, producing ethene from bromoethane.

Why the others are wrong:

• A: Ethanol forms via nucleophilic substitution with OH⁻, replacing Br with OH.
• C: Ethylamine forms via substitution with NH₃, replacing Br with NH₂.
• D: Propanenitrile forms via substitution with CN⁻, yielding CH₃CH₂CN.

Final answer: B