During the thermal decomposition of calcium carbonate, the evolved gas is passed through lime water, which turns milky. This confirms the presence of which gas?
Answer and explanation
Correct answer: Carbon dioxide
The thermal decomposition reaction is \(\mathrm{CaCO_3 \xrightarrow{\Delta} CaO + CO_2}\). The evolved \(\mathrm{CO_2}\) reacts with lime water, \(\mathrm{Ca(OH)_2}\), to form an insoluble white precipitate of \(\mathrm{CaCO_3}\), making the lime water milky. Oxygen supports combustion, but it does not turn lime water milky.
Frequently asked questions
What is the correct answer to this question?
Carbon dioxide
Why is this the correct answer?
The thermal decomposition reaction is \(\mathrm{CaCO_3 \xrightarrow{\Delta} CaO + CO_2}\). The evolved \(\mathrm{CO_2}\) reacts with lime water, \(\mathrm{Ca(OH)_2}\), to form an insoluble white precipitate of \(\mathrm{CaCO_3}\), making the lime water milky. Oxygen supports combustion, but it does not turn lime water milky.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
