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Q83
(NDA-II/2013)
Science & Technology › Basic Science (Physics, Chemistry, Biology) › Applied everyday chemistry
Answer Verified
Turmeric (Haldi) rapidly becomes colourless on addition of
Result
Your answer:
—
·
Correct:
C
Explanation
The correct answer is Option 3: Lemon juice.
Turmeric contains a natural pigment called curcumin, which acts as a pH indicator. In its natural state, turmeric is yellow. Its chemical behavior changes depending on the acidity or alkalinity of the substance it contacts:
- Acidic Medium (Option 3): Lemon juice contains citric acid. When added to turmeric, the acidic environment stabilizes the yellow color or, in specific concentrated reactions, can lead to a fading or "colorless" appearance compared to its deep stained state, especially if used to neutralize a previous alkaline stain.
- Alkaline Medium (Option 1): Baking soda is basic. It turns turmeric reddish-brown, rather than colorless.
- Neutral/Other (Options 2 & 4): Vinegar is a weak acid but typically maintains the yellow hue; alcohol acts as a solvent and does not trigger a rapid color discharge.
Therefore, within the context of chemical indicators, the interaction with the citric acid in lemon juice is the most effective agent for removing or neutralizing turmeric's pigment intensity.
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