Q.

Which one of the following precipitates are formed when the carbon dioxide gas is passed through lime water

1 Ca(OH)2  
2 Ca(OH)4  
3 CaCO3  
4 CaCO2  

Ans.

(3)

When carbon dioxide is passed through lime water, it turns milky due to the formation of white precipitate of calcium carbonate.

Ca(OH)2+CO2CaCO3+H2O