Generated by claude-sonnet-4-6 · 2026-06-15 06:48 · grounding rag
Model Answer
(a)
(i) Methane — CH₄
(ii) Propane — C₃H₈
(b) Carbon compounds are covalently bonded. The intermolecular forces between covalent molecules are weak, so very little energy is needed to overcome them. Hence, carbon compounds have low melting and boiling points.
Source: Chapter 4, Section 4.2.2 (Table 4.2)
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Explanation
- (a) These formulae come directly from Table 4.2. Methane has 1 C and 4 H; Propane has 3 C and 8 H (general alkane formula CₙH₂ₙ₊₂).
- (b) The key idea examiners want: carbon compounds are covalent, and covalent compounds have weak intermolecular forces, hence low melting/boiling points. Always mention both the type of bonding and the weak forces — that's where the mark lies.