Concept:Benzene is unique because it can show both addition reactions and substitution reactions.
Explanation:Benzene has the molecular formula
C6H6.
It contains alternate double bonds, yet it is more stable than expected due to delocalisation of electrons.
Under normal conditions, benzene undergoes substitution reactions rather than addition.
For example, benzene reacts with chlorine in the presence of a catalyst to form chlorobenzene.
This is a substitution reaction.
However, benzene can also undergo addition reactions under special conditions.
When benzene vapour and hydrogen are passed over a nickel catalyst, benzene is converted to cyclohexane.
This addition reaction is called hydrogenation.
Therefore, among the given compounds, benzene can undergo both addition and substitution reactions.
Answer:Benzene