Part of the structures of carbon dioxide and calcium carbide are shown. O=C=O O=C=O O=C=O O=C=O O=C=O O=C=O carbon dioxide (Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ Ca²⁺ C₂²⁻ calcium carbide

1. (a)Explain in terms of structure and bonding why carbon dioxide has a low boiling point and calcium carbide has a high boiling point.[3]
2. (b)Calcium carbide, CaC₂, reacts with water to form ethyne, C₂H₂, and calcium hydroxide. Construct the equation for this reaction.[1]
3. (c)Ethyne is an unsaturated hydrocarbon. State the meaning of the term hydrocarbon.[1]
4. (d)Ethyne is a member of the alkyne homologous series. The molecular formulae of the first four members of the alkyne homologous series are shown. C₂H₂ C₃H₄ C₄H₆ C₅H₈ Predict the formula for the fifth member of the alkyne homologous series.[1]
5. (e)(i)Ethyne reacts with hydrogen in a similar way to ethene reacting with hydrogen. The reaction between ethyne and hydrogen is exothermic. What type of chemical reaction occurs when ethyne reacts with hydrogen?[1]
6. (e)(ii)Predict the molecular formula of a product formed when ethyne reacts with hydrogen.[1]
7. (f)1,2-dichloroethene is produced when excess ethyne reacts with chlorine. The structure of 1,2-dichloroethene is shown. Cl Cl C=C H H Deduce the partial structure of the polymer of 1,2-dichloroethene. Show three repeat units.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.