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  9. Q125

RRB Group D (Level-1 posts) 2022 · Question 125 of 598

Study the given diagram carefully. Which option correctly explains the reason for the appearance of the blue-black color?

  1. APotato juice contains proteins, which turn blue-black with iodine.
  2. BPotato juice contains starch, which turns blue-black with iodine.Correct
  3. CPotato juice contains glucose, which turns blue-black with iodine.
  4. DPotato juice contains fats, which turn blue-black with iodine.

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

Explanation

The blue-black color appears due to the presence of starch in the potato juice, which reacts with iodine to produce this color.

Source: RRB Group D 2022 Prev. Yr. Paper (17 Aug 2022) (Shift 2) - Prepp · reliable-secondary

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