Science (086) — AI-generated practice question

Catenation is the unique ability of carbon atoms to bond with other carbon atoms to form long chains, branched chains, or rings.

Carbon can form long chains and rings because the carbon–carbon bond is very strong and stable, allowing large molecules to exist without breaking down. Also, carbon's small atomic size enables its nucleus to hold the shared electron pairs firmly, making its bonds strong.

Silicon, although it can also show catenation, forms compounds with chains of only up to seven or eight atoms. These silicon–hydrogen compounds are very reactive and unstable because silicon has a larger atomic size, so its bonds are much weaker and less stable than carbon–carbon bonds.

Source: Chapter 4, Section 4.2 Versatile Nature of Carbon

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• 1 mark: Definition of catenation.
• 1 mark: Reason carbon shows catenation extensively — strong C–C bond + small atomic size.
• 1 mark: Why silicon shows it less — larger atom → weaker bonds → reactive/unstable compounds (chains only up to 7–8 atoms).

Examiners expect you to contrast carbon and silicon directly. Mentioning "small size of carbon" is important — many students forget this point. Avoid writing lengthy explanations; these three points, written concisely, earn full marks.