Suppose you have two substances and you know one is a carbohydrate and one is a lipid. How could you tell which one was the carbohydrate and which one was the lipid, if you had available the materials found in a bathroom?

Food testing is the correct option.

Test for starch with iodine soln. The soln will change to blue-black if starch present and retain the color of iodine if not present.

Test for reducing and non-reducing sugars by Copper (II) sulphate, Hcl and naoh.

The Lipids can be tested by Sudan (III). The mixture will form a layer of brick-red ppts.

And to onserve the color change.