A solution turns red litmus blue and does not release carbon dioxide when acid is added. Which substance is most likely?
Answer and explanation
Correct answer: Sodium hydroxide
Turning red litmus blue establishes that the solution is basic. The additional observation excludes carbonate and hydrogencarbonate salts, because both release carbon dioxide when treated with an acid: carbonate gives CO₂ through acid decomposition, and hydrogencarbonate does so as well. Sodium hydroxide is a strong base and neutralises an acid without producing CO₂. Therefore option C is the best answer; the carbonate choices fail the gas test.
Frequently asked questions
What is the correct answer to this question?
Sodium hydroxide
Why is this the correct answer?
Turning red litmus blue establishes that the solution is basic. The additional observation excludes carbonate and hydrogencarbonate salts, because both release carbon dioxide when treated with an acid: carbonate gives CO₂ through acid decomposition, and hydrogencarbonate does so as well. Sodium hydroxide is a strong base and neutralises an acid without producing CO₂. Therefore option C is the best answer; the carbonate choices fail the gas 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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