Multiple choice

Which of the following types of litmus paper is not affected by sulphur dioxide gas?

  1. Dry

  2. Wet

  3. Both (1) & (2)

  4. None of these

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sulphur dioxide (SO2) acts as an acidic gas only in the presence of moisture, where it forms sulphurous acid. Dry litmus paper lacks the water necessary for this reaction, so it remains unaffected.