Chemistry 9701/42 March 2021 | Cambridge AS Level Past Papers With Mark Scheme

1. Understanding the electronic configurations of Co2+ and Co3+ ions and predicting their behavior when exposed to air.
2. Observing the thermal decomposition of hydrated cobalt(II) nitrate and explaining the increased thermal stability of Group 2 nitrates.
3. Using Born-Haber cycles to calculate lattice energies and discussing the comparison between FeO and CaO lattice energies.
4. Explaining disproportionation reactions, writing half-equations, and calculating the mass of iron formed during electrolysis of Fe3O4.
5. Exploring the processes in lithium-ion rechargeable batteries, including oxidation states and overall reaction mechanisms.
6. Analyzing the structure and behavior of the IO3– anion, including its shape and reaction with hot sodium hydroxide.
7. Using data on reaction rates, determining reaction orders, writing rate equations, and calculating the rate constant for hydrogen peroxide decomposition.
8. Understanding solubility and calculating the solubility product of Pb(IO3)2, explaining the effects of temperature on reactions.
9. Describing enzyme catalysis and explaining how fumarase catalyzes a reaction with the aid of labeled diagrams.
10. Analyzing the structure and function of proline, its reactions, and its role in protein synthesis and structure.
11. Conducting chemical reactions in multi-step syntheses of organic compounds and understanding their mechanisms.
12. Exploring electrophoresis of amino acids and predicting their movement based on their isoelectric points in a buffer solution.
13. Understanding the buffer solution formation, its pH, and calculations involving weak acids like ACES in the context of electrophoresis experiments.