The gas released on heating baking soda turns lime water milky. What is the identity of the gas?
Answer and explanation
Correct answer: Carbon dioxide
Baking soda is sodium hydrogen carbonate, NaHCO₃. On heating, it decomposes according to 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂. The released carbon dioxide reacts with limewater, calcium hydroxide, to form insoluble calcium carbonate, making the solution milky: CO₂ + Ca(OH)₂ → CaCO₃ + H₂O. Therefore option A is confirmed.
Frequently asked questions
What is the correct answer to this question?
Carbon dioxide
Why is this the correct answer?
Baking soda is sodium hydrogen carbonate, NaHCO₃. On heating, it decomposes according to 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂. The released carbon dioxide reacts with limewater, calcium hydroxide, to form insoluble calcium carbonate, making the solution milky: CO₂ + Ca(OH)₂ → CaCO₃ + H₂O. Therefore option A is confirmed.
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.
