An unknown gas turns lime water milky but does not give a pop sound near a burning splint. Which gas is it?
Answer and explanation
Correct answer: Carbon dioxide
The governing concept is qualitative gas testing. Carbon dioxide reacts with limewater, calcium hydroxide, to form insoluble calcium carbonate, making the liquid milky: CO₂ + Ca(OH)₂ → CaCO₃ + H₂O. Hydrogen produces a characteristic pop when tested with a burning splint, but that result is absent here. Oxygen supports burning rather than turning limewater milky, and chlorine has different bleaching and reactivity tests. Therefore the gas is carbon dioxide, option A.
Frequently asked questions
What is the correct answer to this question?
Carbon dioxide
Why is this the correct answer?
The governing concept is qualitative gas testing. Carbon dioxide reacts with limewater, calcium hydroxide, to form insoluble calcium carbonate, making the liquid milky: CO₂ + Ca(OH)₂ → CaCO₃ + H₂O. Hydrogen produces a characteristic pop when tested with a burning splint, but that result is absent here. Oxygen supports burning rather than turning limewater milky, and chlorine has different bleaching and reactivity tests. Therefore the gas is carbon dioxide, option A.
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.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
