An acidic gas changes the colour of moist litmus but has no effect on dry litmus. Why does it not affect dry litmus?
Answer and explanation
Correct answer: Ions cannot form without water
Acidic behaviour is observed when the gas dissolves in water and produces ions, especially hydrogen ions or hydronium ions, that interact with the indicator. Moist litmus supplies the necessary water, so the colour changes. Dry litmus has no sufficient water medium for ionisation and the characteristic acidic response is not produced. Thus option A is correct. Dry litmus is not inherently basic, and the other statements are unrelated to indicator chemistry.
Frequently asked questions
What is the correct answer to this question?
Ions cannot form without water
Why is this the correct answer?
Acidic behaviour is observed when the gas dissolves in water and produces ions, especially hydrogen ions or hydronium ions, that interact with the indicator. Moist litmus supplies the necessary water, so the colour changes. Dry litmus has no sufficient water medium for ionisation and the characteristic acidic response is not produced. Thus option A is correct. Dry litmus is not inherently basic, and the other statements are unrelated to indicator chemistry.
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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