Home › BECE (Ghana) › Science › Chemical Reactions › Clear limewater turns milky white when a gas is …
Clear limewater turns milky white when a gas is bubbled through it. Which gas was in the bubbles?
AOxygen gas
BNitrogen gas
CCarbon dioxide
DHydrogen gas
Answer & Solution
Correct answer: C. Carbon dioxide
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_
Related questions
Milk left standing for a few days tastes sour. Which process has produced that taste?During a chemical reaction, what happens to the atoms of the reactants?What do we call the substances that are present before a reaction takes place?What happens to the starting substances during a chemical reaction?During photosynthesis, plants use sunlight to convert CO₂ and water into glucose. This shoIn the decomposition Pb(NO₃)₂ → PbO + 4NO₂ + O₂, the equation as written is:Why does the colour of CuSO₄ solution fade when iron filings are added?Which sequence correctly lists three indicators of a chemical change that occur together i