Which of the following compounds would react with an aqueous solution of bromine at room temperature in the dark?
Show the answer and explanation
Correct answer
B. Ethene
Principle or equation
Alkenes contain a carbon-carbon double bond, which undergoes addition reactions with bromine water, decolorizing it. Alkanes, alcohols, and haloalkanes do not react under these conditions.
Why this answer is correct
Ethene (C2H4) has a double bond. Bromine adds across the double bond to form 1,2-dibromoethane, so the orange/brown bromine water is decolorized. Ethane is saturated and requires UV light for substitution. Ethanol and chloroethane do not react with bromine water at room temperature in the dark.
Example
Bubble ethene gas into bromine water; the color changes from orange to colorless.
This published item includes a stored explanation and passed the platform’s publication workflow. It is independent preparation material, not a claim of an official or recalled examination question.