Question

Egg white turns violet when two drops of copper sulphate and ten drops of caustic soda are added to it. This indicates the presence of
A Starch
B Protein
C Fat
D Vitamins

Answer 1

Hint: The white part of the egg, which contains the most protein and has the fewest calories, is the best source of protein. The cholesterol, lipids, and the majority of the overall calories are carried in the egg yolk. Choline, vitamins, and minerals are also present.

Complete answer:
The presence of protein is detected using a biuret solution. The biuret reagent is a blue solution that turns pink-purple when it reacts with protein.
A positive test shows a vivid blue/purple colour due to the copper ion complexing with the protein's amide group.
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:
Copper ions are reduced to Cuprous ions in the presence of alkaline medium (caustic soda or NaOH) and attach to the egg proteins, resulting in a violet tint.

As a result, the right response is an option B.

Note:
The egg white contains more than half of the protein in an egg and also contains vitamin B2 and less fat than the yolk. Selenium, vitamin D, B6, B12, and minerals including zinc, iron, and copper are all abundant in eggs. The yolks of eggs are higher in calories and fat than the whites.