Why does dry hydrogen chloride gas not turn dry blue litmus paper red?
Answer and explanation
Correct answer: No acidic ions form without water
Hydrogen chloride shows acidic behavior only after dissolving in water. In moist conditions, HCl reacts with water to form hydronium ions and chloride ions: HCl + H2O → H3O+ + Cl−. Hydronium ions cause blue litmus to turn red. Dry HCl gas and dry litmus provide no water for this ionisation, so no color change occurs. Hence option A is correct; HCl is not a base and can form an acid in water.
Frequently asked questions
What is the correct answer to this question?
No acidic ions form without water
Why is this the correct answer?
Hydrogen chloride shows acidic behavior only after dissolving in water. In moist conditions, HCl reacts with water to form hydronium ions and chloride ions: HCl + H2O → H3O+ + Cl−. Hydronium ions cause blue litmus to turn red. Dry HCl gas and dry litmus provide no water for this ionisation, so no color change occurs. Hence option A is correct; HCl is not a base and can form an acid in water.
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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