1. Benedict test is a test for the presence of reducing sugars. The result will be a color from no reaction to extreme being blue, orange, yellow, green, red, brick red, or brown. A positive indication is given if glucose, lactose, or maltose is present. If treated with dilute hydrochloric acid, then sucrose can be detected as well. But if not treated, sucrose isn't detected. Starches do not react, or react very poorly.
Lugol test is a test using iodine to check for the presence of starch. If starch is present, a deep blue-black color will appear.
Biuret test is a test for the presence of peptide bonds which is found in proteins. If peptide bonds are present the solution will turn violet with the intensity of the color being proportional to the concentration of peptide bonds.
Sudan Red test is a test for the presence of lipids (fat). If present, the fats will be stained reddish-orange.
2. Since the white powder is a starch, we will get the following: Benedict test - Clear to light blue. Little to no reaction. Lugol test - deep blue-black color will appear. Positive reaction. Biuret test - remains blue in color, no reaction. Sudan Red test - No red-orange color will appear.
