Why is limewater useful for identifying carbon dioxide in the laboratory?
Answer and explanation
Correct answer: Carbon dioxide forms insoluble calcium carbonate
Limewater is a dilute solution of calcium hydroxide, Ca(OH)₂. When carbon dioxide is bubbled through it, the reaction Ca(OH)₂ + CO₂ → CaCO₃ + H₂O occurs. Calcium carbonate is insoluble and forms a white suspension, making the limewater milky. This visible, characteristic change makes option A correct. The other options give products or colour changes that do not describe this identification test.
Frequently asked questions
What is the correct answer to this question?
Carbon dioxide forms insoluble calcium carbonate
Why is this the correct answer?
Limewater is a dilute solution of calcium hydroxide, Ca(OH)₂. When carbon dioxide is bubbled through it, the reaction Ca(OH)₂ + CO₂ → CaCO₃ + H₂O occurs. Calcium carbonate is insoluble and forms a white suspension, making the limewater milky. This visible, characteristic change makes option A correct. The other options give products or colour changes that do not describe this identification test.
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.
