b
Molisch's Test : This is a general test for carbohydrates. One or two drops of alcoholic solution of \(\alpha\) -naphthol is added to \(2\; ml\) glucose solution. \(1 \mathrm{ml}\) of conc. \(H_{2} S O_{4}\) solution is added carefully along the sides of the test-tube. The formation of a violet ring at the junction of two liquids confirms the presence of a carbohydrare or sugar.