The OCR GCSE Chemistry (Gateway Science) Higher Tier Paper 4 from November 2020 evaluates advanced topics, including the Haber process, bioleaching, dynamic equilibrium, and fractional distillation. Practical assessments involve rates of reaction, titration, and electrolysis. Key areas include reaction mechanisms, polymerisation, atom economy, and environmental chemistry. The paper integrates sustainability, industrial processes, and data interpretation, focusing on real-world chemical applications, material properties, and energy efficiency in industrial synthesis and recycling. Analytical and problem-solving skills are tested through experimental setups and calculations.