1. Take two beakers. Label them as A and B.
2. Fill two beakers upto half with clear lime water.
3. Blow air into beaker ‘A’ using a straw.
4. Pass atmospheric air repeatedly into beaker B’ using a dropper.
5. Observe the colour change in both the beakers.
6. Lime water is clear and colourless, but it turns milky white when it reacts with carbon dioxide.
7. This concludes that there is more carbon dioxide in exhaled air when compared to inhaled air.
