⚡ Show all working — the AI marks against the AQA mark scheme. Method marks awarded for correct working even if the final answer is wrong.
1 markState descriptionAQA 8462 style
Which statement correctly describes the particles in a liquid?
A Particles are in a fixed, regular arrangement with no movement
B Particles are close together, randomly arranged, and able to move past each other
C Particles are far apart and move randomly at high speed
D Particles are in a regular lattice with strong fixed bonds
3 marksExplain high melting pointAQA 8462 P1 style
Sodium chloride has a melting point of 801°C. Explain this in terms of its structure and bonding. (3 marks)
Hint: Name the structure (giant ionic lattice), describe the forces between ions (electrostatic attractions), and explain why lots of energy is needed.
+30 XP
1 markElectrical conductivityAQA 8462 style
Sodium chloride does NOT conduct electricity when solid but DOES conduct when molten. Explain why.
A When solid the ions are bonded; when molten the bonds break and electrons are released
B When solid the ions are in fixed positions; when molten they are free to move and carry charge
C Melting changes NaCl into a metal which conducts electricity
D Solid NaCl has too high a resistance; molten NaCl has lower resistance
3 marksCompare structuresAQA 8462 style
Explain why diamond has a very high melting point but methane (CH₄) has a very low boiling point, even though both contain only covalent bonds. (3 marks)
Hint: Key distinction: diamond has GIANT covalent structure (break actual covalent bonds to melt). Methane has simple molecular structure (only weak forces between molecules broken on boiling).