Question

• A. Potato juice contains proteins, which turn blue-black with iodine.
• B. Potato juice contains starch, which turns blue-black with iodine.
• C. Potato juice contains glucose, which turns blue-black with iodine.
• D. Potato juice contains fats, which turn blue-black with iodine

Answer 1

Answer:

B. Potato juice contains starch, which turns blue-black with iodine.

The blue-black color appears due to the presence of starch in the potato juice,which reacts with iodine to produce this color. Amylose present in starch is the reason for change in its colour to blue black. Iodine is not soluble in water so it is dissolved along with potassium iodide that forms a triiodide molecule which enters the helical structure of amylose and changes the colour of starch