Clear limewater turns milky white when a gas is bubbled through it. Which gas was in the bubbles?

1. Limewater is a solution of calcium hydroxide in water and it starts off clear. 2. Carbon dioxide reacts with it to make calcium carbonate, a white solid. 3. That white solid spread through the water is what makes the liquid look milky. 4. Because only carbon dioxide gives this particular result, the test identifies it. 5. Oxygen, nitrogen and hydrogen give no such colour change in limewater. 6. This is why the milky colour is used as a test for carbon dioxide in breath. _Source: Siyavula Natural Sciences Grade 8 (CC BY 4.0), Some chemical reactions from Life and Living_