Science (086) — AI-generated practice question

Ethyne (C₂H₂) is an unsaturated hydrocarbon containing a carbon–carbon triple bond (C≡C). The extra bonds (pi bonds) are weaker and electron-rich, making them available for addition reactions. Bromine from bromine water adds across the triple bond, decolourising it.

Ethane (C₂H₆) is a saturated hydrocarbon with only single bonds. All valencies are fully satisfied, leaving no electron-rich bonds available for addition. Hence, it does not react with bromine water and cannot decolourise it.

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

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• The key distinction examiners want: saturated vs. unsaturated, and linking that to addition reaction capability.
• Mention the triple bond in ethyne specifically — one mark is typically for bond type, one for the reaction type (addition), one for why ethane does not react.
• Avoid over-explaining; the passage confirms unsaturated compounds "are more reactive than the saturated carbon compounds" — use this directly.