Ten grams of calcium carbonate is heated in a closed container. If no gas escapes, what will be the total mass of the products?
Answer and explanation
Correct answer: Ten grams
On heating, calcium carbonate decomposes according to the reaction CaCO₃ → CaO + CO₂. Although carbon dioxide is produced, the container is closed, so this gas remains inside and is included in the measured products. The law of conservation of mass therefore gives: total mass of products = total mass of reactant = 10 g. Hence option A is correct; the other values incorrectly assume mass is lost, doubled, or absent.
Frequently asked questions
What is the correct answer to this question?
Ten grams
Why is this the correct answer?
On heating, calcium carbonate decomposes according to the reaction CaCO₃ → CaO + CO₂. Although carbon dioxide is produced, the container is closed, so this gas remains inside and is included in the measured products. The law of conservation of mass therefore gives: total mass of products = total mass of reactant = 10 g. Hence option A is correct; the other values incorrectly assume mass is lost, doubled, or absent.
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.
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