In detection of CO2, lime water turns milky due to formation of

→ When CO2 passed through lime water, lime water turned milky due to the formation of CaCO3 precipitate. It indicates the presence of "Carbon".5H2O + CuSO4   →  CuSO4. SH2O          Anhydrous      Blue colour         (Colourless)     [copper sulphate pentahydrate]When liberated H2O is passed through the anhydrous CuSO4, it turned to blue colour due to the formation of CuSO4.5H2O. It indicates the presence of hydrogen.