NEET BIOLOGY

Detailed explanation-1: -Iodine is a common indicator to test for the presence of starch. The light orange-brown colour Iodine solution turns blue-black in colour when it reacts with starch. This indicates the presence of carbohydrates in the food item to which iodine solution was added.

Detailed explanation-2: -Iodine-KI Reagent: Iodine is not very soluble in water, therefore the iodine reagent is made by dissolving iodine in water in the presence of potassium iodide. This makes a linear triiodide ion complex with is soluble that slips into the coil of the starch causing an intense blue-black color.

Detailed explanation-3: -The starch test. Many different food groups contain a carbohydrate known as starch. Using an iodine solution, you can test for the presence of starch. When starch is present, the iodine changes from brown to blue-black or purple.

Detailed explanation-4: -Using iodine to test for the presence of starch is a common experiment. A solution of iodine (I2) and potassium iodide (KI) in water has a light orange-brown color. If it is added to a sample that contains starch, such as the bread pictured above, the color changes to a deep blue.