A gas turns moist blue litmus red but has no effect on dry blue litmus. What does this prove?
Answer and explanation
Correct answer: The gas dissolves in water to form acidic ions
An acid shows its characteristic effect through hydrogen ions, more accurately hydronium ions, in aqueous moisture. The gas does not change dry blue litmus because there is no sufficient water medium for these ions to form and move. When moisture is present, the gas dissolves and reacts with water to produce an acidic solution, which turns blue litmus red. Hence option A is correct; the other choices do not explain the dependence on moisture.
Frequently asked questions
What is the correct answer to this question?
The gas dissolves in water to form acidic ions
Why is this the correct answer?
An acid shows its characteristic effect through hydrogen ions, more accurately hydronium ions, in aqueous moisture. The gas does not change dry blue litmus because there is no sufficient water medium for these ions to form and move. When moisture is present, the gas dissolves and reacts with water to produce an acidic solution, which turns blue litmus red. Hence option A is correct; the other choices do not explain the dependence on moisture.
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.
