Q1.
Do you observe any changes in the colour of the lime water?
Answer
Yes — but only in one of the two test tubes.
| Test tube | Air passed into the lime water | Change observed |
|---|---|---|
| A | Surrounding air, pushed in with a syringe or pichkari — the same air we inhale | Lime water stays clear — no change |
| B | Air blown out from the mouth through a straw — exhaled air | Lime water turns milky (cloudy) |
Tip: take an equal amount of freshly prepared lime water in both tubes. Old lime water has already reacted with the carbon dioxide of the air and may be cloudy before the activity even begins.