Answer:
The test to confirm the presence of starch is Benedict's test
Explanation:
Benedict solution is used to test for simple carbohydrates (reducing sugars such as monosaccharides and some disaccharides). It has a blue colour because of the presence of copper (in the form of CuSO₄) in the benedict solution.
The white powder can be dissolved in water to make a saturated solution. When few drops of benedict's solution (blue colour) is added to about 1 ml of the white powdered solution and then subjected to heat (perhaps in a water bath), a green/yellow/orange/red precipitate will indicate the presence of starch (reducing sugar).
Biuret test is used to test for protein. It also has a blue colour which is also due to the presence of copper (in the form of CuSO₄) in the biuret solution.
When few drops of biuret solution is added to about 1 ml of the white powdered solution, there will be no colour change to violet/pink/purple which would have signified the presence of protein.
Sudan red test is used to identify/test for lipids. It has a red colour as evident from the name. It is a fat-soluble dye and would not dissolve in water. It basically stains lipids.
If few drops sudan red dye is added to the white powdered solution, the solution will not dissolve/stain the solution since it is not soluble in water.
From the above, it can be deduced that Benedict test will confirm the white powder to be starch
