Which of the following is an endothermic reaction?
A. Burning of natural gas
B. Respiration
C. Decomposition of calcium carbonate
D. Reaction of sodium with water
Answer: Option C
Solution (By JKExamLibrary)
Endothermic reactions absorb heat from the surroundings. The decomposition of calcium carbonate (CaCO₃ → CaO + CO₂) requires continuous heating to proceed. Burning of gas, respiration, and the reaction of sodium with water are all exothermic reactions that release significant amounts of heat energy to the surroundings.
Explanation:
Sodium lauryl sulfate (SLS) is a synthetic detergent (surfactant) used in shampoos and toothpaste. Soap is a natural detergent from fats/oils. Starch and cellulose are natural polymers, not detergents. SLS has a sulfate group and works well in hard water.
Explanation:
Centrifugation spins the mixture at high speed, causing denser particles (skimmed milk) to settle at the bottom while lighter cream floats on top. This is based on density differences. Distillation is for liquids, filtration for insoluble solids, sublimation for sublimable solids.
Explanation:
Limestone is CaCO₃. On strong heating, it decomposes to calcium oxide (quicklime) and carbon dioxide: CaCO₃ → CaO + CO₂. This is a decomposition reaction used in cement and lime manufacturing. CaO is used in building and as a drying agent.
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