1. What three elements are required for fire to occur? A) Heat, fuel, and carbon dioxide B) Heat, fuel, and water C) Heat, fuel, and oxygen D) Heat, fuel, and nitrogen 2. What type of change occurs when matter changes its shape, size, or state without changing its composition? A) Chemical change B) Physical change C) Combustion D) Oxidation 3. Which process requires the presence of oxygen and results in the formation of a new substance? A) Freezing B) Melting C) Combustion D) Evaporation 4. Rust is formed when iron reacts with: A) Water alone B) Carbon dioxide in the air C) Oxygen in the air D) Heat 5. What substance is commonly called rust? A) Iron oxide B) Iron chloride C) Iron sulfide D) Iron nitrate 6. Which of the following best describes the rusting process? A) A rapid chemical change B) A slow chemical change C) A physical change D) An exothermic reaction 7. How can rusting of iron be prevented? A) Keeping metals clean and dry B) Exposing metals to oxygen C) Heating metals continuously D) Adding water to metals regularly 8. What happens to fruits like apples and bananas when they are cut and exposed to oxygen? A) They freeze B) They ripen C) They turn brown D) They become sour 9. What causes the discoloration of fruits and vegetables when exposed to oxygen? A) Enzymes reacting with oxygen B) Loss of moisture C) Increase in temperature D) Absorption of carbon dioxide 10.What can be done to prevent sliced fruits from turning brown? A) Soaking them in lemon juice or cold water B) Heating them to high temperatures C) Exposing them to direct sunlight D) Covering them with salt 11.What is the main factor that causes food spoilage? A) Lack of sunlight B) Presence of oxygen C) Exposure to cold temperatures D) Absence of moisture 12.Why should food be covered tightly? A) To protect it from insects B) To reduce its exposure to oxygen C) To increase its moisture content D) To keep it warm 13.In the context of changes in materials, which of the following is a chemical change? A) Melting of ice B) Burning of wood C) Breaking of glass D) Freezing of water 14.What change occurs when water evaporates? A) Physical change B) Chemical change C) Both physical and chemical change D) No change 15.Which element is crucial for the combustion process to occur? A) Nitrogen B) Hydrogen C) Oxygen D) Carbon dioxide 16.Which of the following will NOT prevent the rusting of iron? A) Painting the metal B) Keeping the metal dry C) Covering the metal with oil D) Exposing the metal to humid air 17.Which is a correct example of a physical change? A) Burning of paper B) Rusting of iron C) Freezing of water D) Cooking of food
Answer (1)
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