Question

On passing co2 gas through freshly prepared limewater why does it turns milky

Answer 1

due to the formation of CaCO3

Answer 2

Freshly prepared limewater turns milky on passing CO2 in it. This is due to formation of white precipitate of calcium carbonate.

       

                     Ca(OH)2 + Co2  -------->  CaCO3 + H2O

                                                            (white ppt)