Question

Given below from (i) to (iv) are some food items.

1. Boiled and mashed potato
2. Glucose solution
3. A slice of bread
4. Mustard oil

Which of the above will give a blue-black colour when tested with iodine?

Options

• (i) and (ii)

• (i) and (iii)

• (ii) and (iii)

• (iii) and (iv)

Answer 1

(i) and (iii)

Explanation:

When iodine is added to starch, it turns blue-black in colour. Potato and bread are rich in starch. Therefore, boiled and mashed potato and a slice of bread turn blue-black in colour when tested with iodine. Glucose solution does not change colour because it is a digestive product of starch.