Combined Science (A) J250,10 Higher June 2019, OCR GCSE Past Papers with Mark Schemes

1. Chemical Reactions and Reactivity – Factors affecting reaction rates, balancing chemical equations, and explaining displacement reactions in halogens.

2. Fractional Distillation and Hydrocarbon Properties – Relationship between intermolecular forces, boiling points, and hydrocarbon chain length in crude oil fractions.

3. Acid-Base and Displacement Reactions – Identifying products of acid-metal reactions, testing for gases like CO₂, H₂, and O₂, and explaining neutralization reactions.

4. Environmental Chemistry and Pollution – Causes and effects of acid rain, sources of sulfur dioxide emissions, and environmental impact of fossil fuel combustion.

5. Equilibrium and Industrial Chemistry – Effects of concentration, pressure, and temperature on equilibrium position and reaction yield in chemical processes.

6. Energy and Bond Calculations – Calculating enthalpy changes using bond enthalpies, interpreting energy profiles, and determining energy released in combustion reactions.