Question

what is lime-water test for the detection of carbon dioxide?

Answer 1

Well, lime water is simply Calcium hydroxide Ca(OH)2 it is a colorless solution and well it is basic/ alkaline cause of various reasons some of which are it turns red litmus blue and can react whit acids through a neutralization reaction.

Anyway you basically wanted to know what it is used for. Lime water is used to test for presence of Carbon dioxide in the lab when Carbondioxide passes through it turns from colorless to cloudy white substance which is called Calcium Carbonate

Answer 2

lime water means calcium hydroxide .....
when cardondioxide is passed through calcium hydroxide then calcium carbonate is formed which gets suspended and hence turns the solution milky ...
extra...
if the carbon dioxide is passing continues the calcium bicarbonate is formed which is soluble hence that lime water again be comes clear and if you boil it the again you will see the lime water milky