A solution turns red litmus blue. When ammonium chloride is added to it and heated, a pungent-smelling gas is evolved. Which gas is it?
Answer and explanation
Correct answer: Ammonia
Turning red litmus blue shows that the solution contains a base, such as sodium hydroxide. On heating with ammonium chloride, the base releases ammonia: NaOH + NH₄Cl → NH₃ + H₂O + NaCl. Ammonia has a characteristic pungent smell and turns moist red litmus blue. Hydrogen, carbon dioxide and sulphur dioxide do not fit these observations, so A is correct.
Frequently asked questions
What is the correct answer to this question?
Ammonia
Why is this the correct answer?
Turning red litmus blue shows that the solution contains a base, such as sodium hydroxide. On heating with ammonium chloride, the base releases ammonia: NaOH + NH₄Cl → NH₃ + H₂O + NaCl. Ammonia has a characteristic pungent smell and turns moist red litmus blue. Hydrogen, carbon dioxide and sulphur dioxide do not fit these observations, so A is correct.
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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