Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Simple molecular structures
19 practice questions
Practice questions
1–3 of 3 · Hard
Question 1
2 marks · Hard
Answer and see the solution →Explain, using ideas about bonds and forces, why melting a substance with a simple molecular structure requires much less energy than melting a giant covalent structure such as diamond.
Question 2
5 marks · Hard
Answer and see the solution →The table shows data for three simple molecular substances:
Substance Relative molecular mass (Mr) Melting point (°C) Boiling point (°C) Electrical conductivity A 32 -210 -183 does not conduct B 44 -56 -1 does not conduct C 160 -7 59 does not conduct (a)[2 marks]Describe the trend shown by the melting points and boiling points as the relative molecular mass increases.
(b)[2 marks]Substance C is liquid at room temperature (25°C). Explain why substance C is a liquid at this temperature but substance A is a gas.
(c)[1 mark]Explain why none of these substances conduct electricity in any state.
Question 3
2 marks · Hard
Answer and see the solution →State one property that distinguishes a simple molecular structure from a giant covalent structure. Explain how this property relates to the forces present in each structure.