Science (086) — AI-generated practice question

Ethyne (C₂H₂) contains a triple bond between its two carbon atoms (C≡C). This means its carbon atoms are not bonded to the maximum possible number of hydrogen atoms, making it an unsaturated compound. Ethane (C₂H₆), on the other hand, has only single bonds with all valencies satisfied by hydrogen atoms, so it is saturated.

The triple bond in ethyne makes it more reactive because it can undergo addition reactions, where other atoms or groups add across the multiple bond. Saturated ethane, having no such multiple bonds, is fairly unreactive and undergoes only slow substitution reactions.

Source: Chapter 4, Section 4.2.1 – Saturated and Unsaturated Carbon Compounds

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• Key structural point (1 mark): Ethyne has a C≡C triple bond; ethane has only C–C single bonds.
• Definition link (1 mark): Unsaturated = double or triple bond present; saturated = only single bonds.
• Reactivity reason (1 mark): Multiple bonds allow addition reactions; single bonds allow only slow substitution — examiners expect this contrast explicitly stated.
• Don't just say "more bonds = more reactive"; name the type of reaction (addition vs. substitution).