Air blown into limewater, turns it milky. This confirms the presence of in air.
The correct option is A carbon dioxide
When air is blown into limewater, the solution turns milky. This confirms the presence of carbon dioxide (CO2) in air. This is because CO2 reacts with limewater(Ca(OH)2) and forms insoluble calcium carbonate (CaCO)3 which is 'white' in colour.
The suspended particles of white calcium carbonate settle down after some time.
The chemical reaction involved is: