Why does dry hydrochloric acid gas not change the colour of dry litmus paper?
Answer and explanation
Correct answer: Water is absent
The governing concept is that hydrochloric acid shows acidic behaviour only after ionisation in water. Dry hydrogen chloride gas cannot provide hydrogen ions to dry litmus because there is no water to form hydronium ions. Therefore option A is correct. The acid is present, the litmus need not be damaged, and hydrogen chloride is not a basic gas; the missing condition is moisture.
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What is the correct answer to this question?
Water is absent
Why is this the correct answer?
The governing concept is that hydrochloric acid shows acidic behaviour only after ionisation in water. Dry hydrogen chloride gas cannot provide hydrogen ions to dry litmus because there is no water to form hydronium ions. Therefore option A is correct. The acid is present, the litmus need not be damaged, and hydrogen chloride is not a basic gas; the missing condition is 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.
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