A sample is heated, gas is released, and the solution of the remaining solid is basic. If the sample was baking soda, what is the remaining solid?
Answer and explanation
Correct answer: Sodium carbonate
The governing concept is thermal decomposition of sodium hydrogen carbonate, commonly called baking soda. On heating, 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂. The released carbon dioxide accounts for the gas, while the remaining sodium carbonate dissolves to give a basic solution because carbonate ions hydrolyse water and produce hydroxide ions. Thus option B is correct; the other substances are not the solid product of this decomposition.
Frequently asked questions
What is the correct answer to this question?
Sodium carbonate
Why is this the correct answer?
The governing concept is thermal decomposition of sodium hydrogen carbonate, commonly called baking soda. On heating, 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂. The released carbon dioxide accounts for the gas, while the remaining sodium carbonate dissolves to give a basic solution because carbonate ions hydrolyse water and produce hydroxide ions. Thus option B is correct; the other substances are not the solid product of this decomposition.
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.
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