This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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You're on a roll — here are the answers to the multiple-choice questions. 38. Which set of elements represents the major nutrients required by plants for healthy growth? The major nutrients (macronutrients) required by plants are Nitrogen (N), Phosphorus (P), and Potassium (K). The correct option is A. A. Nitrogen, phosphorus and potassium 39. Which property of water involves a chemical change? A chemical change results in the formation of new substances. A. Freezing at 0\,^C is a physical change (liquid to solid). B. Boiling at 100\,^C is a physical change (liquid to gas). C. Evaporation is a physical change (liquid to gas). D. Reaction with sodium involves water reacting to form hydrogen gas and sodium hydroxide, which is a chemical change. The correct option is D. D. Reaction with sodium 40. Which sequence best represents the stages in water treatment? The typical sequence for water treatment involves removing large debris (screening), allowing solids to settle (sedimentation), filtering out smaller particles (filtration), and disinfecting (chlorination). The correct option is A. A. Sedimentation → filtration → chlorination 41. Calculate the amount of substance in 20g of C_6H_12O_6. [C=12, H=1, O=16] Step 1: Calculate the molar mass of C_6H_12O_6. Molar mass = (6 × 12) + (12 × 1) + (6 × 16) Molar mass = 72 + 12 + 96 = 180 g/mol Step 2: Calculate the amount of substance (moles). Moles = MassMolar mass Moles = 20g180 g/mol Moles ≈ 0.111 mol The closest option is A. A. 0.11mol 42. Which of the following practices cannot cause diseases in man? A. Living in poor environment can lead to diseases due to poor sanitation and exposure to pathogens. B. Keeping good personal hygiene helps prevent diseases. This practice cannot* cause diseases. C. Eating unbalanced meals can lead to nutritional deficiencies and related diseases. D. Unnecessary stress can weaken the immune system and contribute to various health issues. The correct option is B. B. Keeping good personal hygiene 43. Which of the following cannot be used to control pollution in Ghana? A. Planting and caring trees helps absorb carbon dioxide and prevent soil erosion, controlling pollution. B. Placing liquid and semi-liquid wastes in unlined pits allows pollutants to seep into the ground and water, causing* pollution, not controlling it. C. Excessive use of agrochemicals in agriculture causes pollution, it does not control it. D. Collection and proper recycling of waste materials helps reduce waste and pollution. The question asks what cannot be used to control pollution. Both B and C describe actions that cause pollution. However, placing waste in unlined pits is a direct act of pollution, while excessive use of agrochemicals is a practice that leads to pollution. Option B is a direct method of not controlling pollution. The correct option is B. B. Placing liquid and semi-liquid wastes in unlined pits 44. Group VIII elements are... Group VIII elements (also known as Group 18 or noble gases) are characterized by their full outer electron shells, making them very stable and unreactive. The correct option is B. B. unreactive 45. One of the following cannot be used to control food poisoning? A. Good hygienic practices prevent contamination. B. Improper storage and temperature control causes* food poisoning, it does not control it. C. Safe water supply prevents waterborne pathogens. D. Routine inspection and proper regulation ensures food safety standards. The correct option is B. B. Improper storage and temperature control 46. Metals react with acid to liberate... When reactive metals react with dilute acids, they typically displace hydrogen from the acid, producing a salt and hydrogen gas. The correct option is B. B. hydrogen gas 47. All the following are symptoms of food poisoning except... Food poisoning commonly causes gastrointestinal symptoms. A. A cough is typically a respiratory symptom, not directly associated with food poisoning. B. Nausea is a common symptom. C. Vomiting is a common symptom. D. Fever can occur with food poisoning. The correct option is A. A. cough 48. Which one of the following does not bring about indigestion in man? A. Eating too much acidic foods can cause indigestion. B. Eating at irregular times can disrupt digestion. C. Eating enough roughage (fiber) aids digestion and prevents indigestion. This does not cause indigestion. D. Improper chewing of food makes it harder to digest. The correct option is C. C. Eating enough roughage 49. Which of the following elements is a halogen? Halogens are elements in Group 17 of the periodic table. A. Chlorine is a halogen. B. Oxygen is in Group 16. C. Magnesium is an alkaline earth metal (Group 2). D. Sulphur is in Group 16. The correct option is A. A. Chlorine 50. Which of the following is an alkali metal? Alkali metals are elements in Group 1 of the periodic table. A. Sodium is an alkali metal. B. Carbon is a non-metal (Group 14). C. Magnesium is an alkaline earth metal (Group 2). D. Chlorine is a halogen (Group 17). The correct option is A. A. Sodium Got more? Send 'em!