Question

A few drops of iodine solution were added to rice water. The solution turned blue-black in color. This indicates that rice-water contains

• A. Complex proteins
• B. Simple proteins
• C. Fats
• D. Starch

Answer 1

The correct option is D

Starch

The correct option is D.

Explanation of Correct Option:

• The iodine is the chemical added to the rice water solution to test the presence of a polysaccharide carbohydrate called starch.
• The iodine creates a complex with the starch that changes the color of the solution. The solution will have a blue-black color.

Explanation of Incorrect Options:

Option A:

• The iodine does not react with complex proteins to give a blue-black color.

Option B:

• The biuret test detected the presence of proteins, not the iodine test.

Option C:

• The iodine is not used to test for the presence of fats. It is used to detect starch.

Therefore, the blue-black color of rice solution after adding iodine will indicate the presence of starch.