Question

why lime water turns my milky on passing carbon-dioxide gas into it

Answer 1

because it reacts with lime water to form another compound which is milky in colo

Answer 2

Lime water is actually Ca(OH)2 . When it reacts with CO2 insoluble CaCO3 is formed which turns solution milky. ... When carbon dioxide is passed through lime water it turns milky due to the formation of water insoluble precipitate CaCO3. Still if excess of CO2 is passed it forms water soluble Calcium bicarbonate .