How will you detect the presence of carbon and hydrogen in an organic compound ?
The detection of carbon and hydrogen in an organic compound is done by a single experiment. A small quantity of dry and powdered organic compound is mixed with 4-5 times its weight of dry cupric oxide. The mixture is taken in a hard glass test tube fitted with a delivery tube having a small bulb in it. The other end of the delivery tube is immersed in freshly prepared lime water taken in another test tube. In the bulb of the delivery tube, a small amount of anhydrous copper sulphate (white) is placed. The mixture is heated strongly when carbon and hydrogen present are oxidised to carbon dioxide and water respectively.
Carbon dioxide turns lime water milky whereas water vapours turn colourless copper sulphate blue. 
Turning of lime water milky and of colourless copper sulphate blue shows the presence of carbon and hydrogen respectively.
