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: Question 38: Which set of elements represents the major nutrients required by plants for healthy growth? A. Nitrogen, phosphorus and potassium These are the primary macronutrients (N-P-K) essential for plant growth. Question 39: Which property of water involves a chemical change? D. Reaction with sodium Freezing, boiling, and evaporation are physical changes (changes of state). Reacting with sodium involves forming new substances (sodium hydroxide and hydrogen gas), which is a chemical change. Question 40: Which sequence best represents the stages in water treatment? A. Sedimentation → filtration → chlorination This sequence represents the common steps: sedimentation to settle heavy particles, filtration to remove suspended solids, and chlorination for disinfection. Question 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 Molar mass = 180\, g/mol Step 2: Calculate the amount of substance (moles). Moles = MassMolar mass Moles = 20\, g180\, g/mol Moles = (1)/(9)\, mol ≈ 0.1111\, mol A. 0.11mol Question 42: Which of the following practices cannot cause diseases in man? B. Keeping good personal hygiene Good personal hygiene helps prevent diseases, rather than causing them. Question 43: Which of the following cannot be used to control pollution in Ghana? B. Placing liquid and semi-liquid wastes in unlined pits Placing wastes in unlined pits leads to soil and water contamination, thus causing pollution, not controlling it. Question 44: Group VIII elements are ... B. unreactive Group VIII (or Group 18) elements are noble gases, which are known for their chemical inertness or unreactivity. Question 45: One of the following cannot be used to control food poisoning? B. Improper storage and temperature control Improper storage and temperature control are causes of food poisoning, not methods to control it. Question 46: Metals react with acid to liberate... B. hydrogen gas Reactive metals react with acids to produce a salt and hydrogen gas. Question 47: All the following are symptoms of food poisoning except... A. cough Nausea, vomiting, and fever are common symptoms of food poisoning. A cough is typically a symptom of respiratory illness. Question 48: Which one of the following does not bring about indigestion in man? C. Eating enough roughage Eating enough roughage (fiber) aids digestion and helps prevent indigestion. The other options can contribute to indigestion. Question 49: Which of the following elements is a metal? C. Magnesium Chlorine, Oxygen, and Sulphur are non-metals. Magnesium is an alkaline earth metal. Question 50: Which of the following is an example of group VII elements? D. Chlorine Group VII (or Group 17) elements are the halogens, which include Chlorine. What's next?