A substance dissolves in water to form a basic solution and gives carbon dioxide with acid. What is the most suitable identification?
Answer and explanation
Correct answer: Sodium carbonate
The decisive test is the reaction with an acid. Carbonates react with acids to release carbon dioxide; for example, Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂. Sodium carbonate is also a basic salt because the carbonate ion hydrolyses in water and produces OH⁻ ions, making its aqueous solution alkaline. Therefore option C satisfies both observations. Sodium chloride is essentially neutral, ammonium chloride gives an acidic solution, and copper sulphate does not give carbon dioxide in this test.
Frequently asked questions
What is the correct answer to this question?
Sodium carbonate
Why is this the correct answer?
The decisive test is the reaction with an acid. Carbonates react with acids to release carbon dioxide; for example, Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂. Sodium carbonate is also a basic salt because the carbonate ion hydrolyses in water and produces OH⁻ ions, making its aqueous solution alkaline. Therefore option C satisfies both observations. Sodium chloride is essentially neutral, ammonium chloride gives an acidic solution, and copper sulphate does not give carbon dioxide in this test.
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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