bed dissolved carbon dioxide and converted it into calcium carbonate ($\\text{CaCO}_3$) shells via anaerobic respiration.","correct":false,"markscheme":"Respiration releases carbon dioxide rather than absorbing it, and photosynthesis produces organic molecules (like glucose) rather than inorganic calcium carbonate shells.","order":2},{"id":"b1c5f18b-572a-4f8f-9ecb-5905dec3e67b","content":"Gaseous carbon dioxide reacted directly with silicon dioxide ($\\text{SiO}_2$) minerals in surface rocks during dry weathering to produce solid calcium carbonate ($\\text{CaCO}_3$) and quartz.","correct":false,"markscheme":"Silicon dioxide ($\\text{SiO}_2$) contains no calcium, so it cannot react with carbon dioxide to form calcium carbonate. Chemical weathering of silicates requires liquid water and involves silicate minerals like calcium silicate ($\\text{CaSiO}_3$).","order":3}],"explanation":null,"firstAttemptFullMarks":null,"walkthroughVideo":null},{"id":"9b46ffaa-6624-482b-a8a2-2c51ed19464c","revisionId":"2c1cba84-f466-420b-80ad-ce2a39b51ff4","questionNumber":null,"questionType":"LA","specification":"","difficulty":3,"difficultyBand":"medium","totalMarks":4,"sourceTitle":null,"calculatorUse":null,"isCalculation":false,"parts":[{"id":"2ec42610-3abf-4791-842a-3b284af8b07e","label":null,"content":"Identify and describe two distinct human activities that have led to an increase in the concentration of carbon dioxide ($CO_2$) in today's atmosphere.","markscheme":"- Combustion of fossil fuels (e.g., coal, oil, gas) for transport, heating, or electricity generation, which releases stored carbon as $CO_2$ into the atmosphere B1\n- Deforestation (clearing forests), which reduces the amount of carbon dioxide removed from the atmosphere via photosynthesis, or releases $CO_2$ when trees are burned/decayed B1\n- Cement manufacture, where the thermal decomposition of limestone ($CaCO_3$) releases carbon dioxide as a chemical byproduct B1\n- Large-scale waste incineration, which involves burning carbon-containing materials and releasing $CO_2$ B1","marks":4,"order":0,"markingRubric":null,"tableImages":[],"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null,"walkthroughVideo":null},{"id":"a6281d92-5500-42b0-98a5-fac905882371","revisionId":"032cd578-44d8-4ff5-bcda-2ded15896542","questionNumber":null,"questionType":"LA","specification":"Table 1 shows the estimated percentages of different gases in the Earth's primeval atmosphere compared with the atmosphere today.\n\n### Table 1\n\n| Gas | Percentage (%) in Earth's primeval atmosphere | Percentage (%) in today's atmosphere |\n| :--- | :---: | :---: |\n| Gas R | 95.5 | 0.04 |\n| nitrogen | 3.2 | 78.1 |\n| oxygen | <0.05 | 20.9 |\n| argon | <0.1 | 0.93 |\n| water vapour | 1.0 | <0.1 |","difficulty":4,"difficultyBand":"medium","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"isCalculation":true,"parts":[{"id":"87481bf6-6198-470f-9045-208bd54e76d2","label":null,"content":"Explain, using the data in Table 1, the identity of **Gas R**.","markscheme":"- Identifies **Gas R** as carbon dioxide, referencing the table data showing its percentage decreased significantly from $95.5\\%$ in the primeval atmosphere to $0.04\\%$ today. M1\n- Explains that this decrease occurred because carbon dioxide dissolved in the oceans (to form carbonate sediments/rocks) or was taken in by photosynthesising algae/plants. A1","marks":2,"order":0,"markingRubric":null,"tableImages":[],"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null,"walkthroughVideo":null}],"subjectCode":"gcse_chemistry","summaries":[{"id":"013547f5-8a43-437e-ac62-3797c3e7257b","difficultyBand":"easy","calculatorUse":null,"totalMarks":1},{"id":"013ed1c2-c8a4-4e08-b0ba-bcb1a0695f4e","difficultyBand":"easy","calculatorUse":null,"totalMarks":2},{"id":"0331d44a-744b-48be-b9cf-b0a5a69afb48","difficultyBand":"easy","calculatorUse":null,"totalMarks":1},{"id":"03d79396-9508-44ef-856a-d9fe

Earth and atmospheric science

Question 12

Earth and atmospheric science Questions

Earth and atmospheric science

Question 12

Earth and atmospheric science Questions