Chemical energetics — IGCSE Science - Combined (0653) questions by topic
Energy level diagrams and exothermic-versus-endothermic reasoning define this topic: explaining nitrogen monoxide's energy level diagram, interpreting thermometer readings before and after mixing ammonium nitrate with water, and selecting the correct bond-energy statement for an exothermic reaction. Explain, draw and identify lead the command words, and explain wants bond-breaking and bond-making energy compared directly, not just a temperature change described.
With 9 real questions from 2024 to 2025 papers and marks from 1 to 8, single-mark identification sits beside multi-step energy-diagram explanations. Practising with instant marking is useful here, since it checks quickly whether an exothermic or endothermic classification is backed by the correct bond-energy comparison rather than just the observed temperature change.
May–June 2025, Paper 11
The initial temperature of a sample of water is measured. Ammonium nitrate is mixed with the water. The final temperature is measured. The diagram shows the thermometer readings.…
Answer this question and get it marked →May–June 2025, Paper 12
Which reaction is most endothermic? initial temperature /°C final temperature /°C --- --- --- A 21 19 B 20 22 C 19 18 D 18 23
Answer this question and get it marked →May–June 2025, Paper 13
Magnesium ribbon is added to dilute hydrochloric acid at 20 degrees C. The mixture starts to fizz and the temperature increases to 32 degrees C. The fizzing then stops and the…
Answer this question and get it marked →May–June 2025, Paper 21
The reaction pathway diagrams for reaction X and for reaction Y are shown. In reaction X the products are at a lower energy than the reactants (energy released). In reaction Y the…
Answer this question and get it marked →May–June 2025, Paper 22
Which statement explains why a reaction is exothermic? A More thermal energy is absorbed by breaking bonds than is released by making bonds. B More thermal energy is absorbed by…
Answer this question and get it marked →May–June 2025, Paper 23
The reaction pathway diagram for a reaction is shown. The vertical axis is energy and the horizontal axis is progress of reaction. Three energy levels are marked X (lowest, the…
Answer this question and get it marked →May–June 2024, Paper 41
Nitrogen and oxygen react together in a car engine to make nitrogen monoxide, NO. Fig. 5.1 shows part of the energy level diagram for this reaction (energy on the vertical axis…
Answer this question and get it marked →May–June 2024, Paper 42
Nitrogen and oxygen react together at high temperatures in car engines to form oxides of nitrogen. Nitrogen monoxide, NO, is one of the oxides of nitrogen. Fig. 5.1 shows the…
Answer this question and get it marked →May–June 2024, Paper 43
Oxides of nitrogen are pollutant gases formed in car engines. Nitrogen, N2, and oxygen, O2, react together in car engines to make nitrogen monoxide, NO. Nitrogen monoxide reacts…
Answer this question and get it marked →Other IGCSE Science - Combined topics
- Practical skills (96)
- Motion, forces and energy (53)
- Electricity and magnetism (38)
- Waves (32)
- Human nutrition (23)
- Acids, bases and salts (22)
- Organisms and their environment (21)
- Organic chemistry (21)
- Reproduction (20)
- Thermal physics (20)
- Plant nutrition (19)
- The Periodic Table (18)