nown sample from a solid to a liquid state at a constant rate.\n\nThe graph shows how the temperature of the sample varies with time during the heating process.\n\n![Heating curve of the unknown metal sample](https://assets.mathsgenie.co.uk/aqa-qb/28afe07b-d180-4449-b0bf-447e7ee95bc2.png)\n\nThe engineer has a sample of mass \$1.5\\text{ kg}\$ and records that it requires \$292.5\\text{ kJ}\$ of thermal energy to raise its temperature from the lowest temperature to the highest temperature within its liquid state.","difficulty":7,"difficultyBand":"medium","totalMarks":9,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"7ba9b17c-6185-43fc-8aff-bd08dcc1eab9","label":"a","content":"Use the graph to calculate the specific heat capacity of the substance. Suggest which material from the table it is most likely to be.","markscheme":"- Identifies the melting point as $300^\\circ\\text{C}$ and the boiling point as $800^\\circ\\text{C}$ from the graph plateau lines M1\n- Calculates the temperature change in the liquid state: $\\Delta \\theta = 800^\\circ\\text{C} - 300^\\circ\\text{C} = 500^\\circ\\text{C}$ A1\n- Converts energy to Joules: $E = 292.5\\text{ kJ} = 292,500\\text{ J}$ B1\n- Recalls or uses the formula $c = \\frac{E}{m \\Delta \\theta}$ M1\n- Calculates specific heat capacity: $c = \\frac{292,500}{1.5 \\times 500} = 390\\text{ J/kg}^\\circ\\text{C}$ A1\n- Suggests **Zinc** based on the matching value in the table A1","marks":6,"order":0,"markingRubric":null,"explanation":null,"options":[]},{"id":"d3ff724b-2bff-400c-ad9a-548cd9374d8b","label":"b","content":"Suggest two reasons why the engineer cannot be certain of this identification.","markscheme":"- Heat loss: some thermal energy is transferred to the vacuum furnace surroundings/crucible rather than the sample, so the actual energy absorbed is lower than recorded. B1\n- Impurity/composition: the sample could be an alloy or have impurities that deviate its specific heat capacity slightly from the pure element. B1\n- Alternative materials: there could be other materials not listed in the table with a similar specific heat capacity (such as Brass at $380\\text{ J/kg}^\\circ\\text{C}$ which is very close). B1","marks":3,"order":1,"markingRubric":null,"explanation":{"methods":[{"id":"evaluate_identification","label":"Evaluate the identification","steps":[{"type":"text","order":1,"title":"Allow for heat loss","content":"Not all of the recorded thermal energy has to enter the metal sample. Some can be transferred to the vacuum furnace surroundings or the crucible holding the sample.\n\nSo the energy absorbed by the sample is lower than the recorded energy. Using the recorded energy would therefore make the calculated specific heat capacity inaccurate. This earns **B1**.","highlights":[{"text":"inside a vacuum furnace","location":"specification"},{"text":"requires \$292.5\\text{ kJ}\$ of thermal energy","location":"specification"}]},{"type":"text","order":2,"title":"Question sample purity","content":"The sample may not be a pure element: it could be an **alloy** (a mixture containing metals) or contain impurities. Its specific heat capacity could then differ slightly from that of the pure metal used for the identification.\n\nThat means a match with a table value does not prove the sample is that pure material. This earns **B1**.","highlights":[{"text":"unknown metal sample","location":"specification"},{"text":"specific heat capacities of several candidate materials","location":"specification"}]}]}],"generatedAt":"2026-07-22T08:45:29.605Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null}],"subjectCode":"gcse_physics__ocr","summaries":[{"id":"08e06023-63ee-40c4-b4a0-19ded34bba21","difficultyBand":"medium","calculatorUse":null},{"id":"096724a7-939b-40b8-bb5a-a05ce6ff869d","difficultyBand":"medium","calculatorUse":null},{"id":"0a82a4b6-66c

Changes of state

Question 9

Changes of state Questions

Changes of state

Question 9

Changes of state Questions