# In an experiment, Radha took small amounts of an unknown food item in a test tube. Then, she added two drops of copper sulphate solution in the test tube along with a few drops of caustic soda solution. After a few minutes, the color of the food item changed to violet. In the given experiment, the change in color of the food item to violet indicates the presence of

Verified
78.6k+ views
Hint: When caustic soda and copper sulphate solution are mixed in a test tube, the colour changes to violet. This test is used to determine how much protein is contained in food molecules. Caustic soda raises the pH, causing the colour to shift from blue to violet.

Egg becomes violet when two drops of copper sulphate and ten drops of caustic soda or NaOH are put to it. This shows that proteins are present. This is Biuret's test, and the concept is straightforward. $C{u^{2 + }}$ions are reduced to $C{u^ + }$ and attach to the egg proteins in the presence of alkaline media (caustic soda or NaOH), resulting in a violet tint.