Which test is used to identify carbon dioxide gas?
Answer and explanation
Correct answer: Lime water turning milky
Carbon dioxide is identified by passing it through limewater, an aqueous solution of calcium hydroxide. The gas reacts to form insoluble calcium carbonate, making the limewater appear milky: CO₂ + Ca(OH)₂ → CaCO₃ + H₂O. Hence option B is correct. A pop sound identifies hydrogen, while litmus or unchanged turmeric does not specifically confirm carbon dioxide.
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What is the correct answer to this question?
Lime water turning milky
Why is this the correct answer?
Carbon dioxide is identified by passing it through limewater, an aqueous solution of calcium hydroxide. The gas reacts to form insoluble calcium carbonate, making the limewater appear milky: CO₂ + Ca(OH)₂ → CaCO₃ + H₂O. Hence option B is correct. A pop sound identifies hydrogen, while litmus or unchanged turmeric does not specifically confirm carbon dioxide.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
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