Question:
The highly alkaline chemical agent which is most commonly used in the formulation of cosmetic depilatories to chemically break the strong disulfide (−S−S−) bonds of hair keratin is
The highly alkaline chemical agent which is most commonly used in the formulation of cosmetic depilatories to chemically break the strong disulfide (−S−S−) bonds of hair keratin is
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Depilatories are cosmetic products that remove unwanted hair by chemically dissolving it. Hair is made of keratin, a tough protein held together largely by disulfide (−S−S−) bonds.
Updated On: Jun 24, 2026
- Hydrogen peroxide
- Sodium lauryl sulfate
- Calcium thioglycolate
- Aluminum chlorohydrate
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The Correct Option is C
Solution and Explanation
Concept:
Depilatories are cosmetic products that remove unwanted hair by chemically dissolving it. Hair is made of keratin, a tough protein held together largely by disulfide (−S−S−) bonds. To break the hair, the depilatory must reduce and cleave these disulfide bridges.
Step 1: Thioglycolate salts are the standard reducing agents for this job. Calcium thioglycolate, used under alkaline conditions, breaks the disulfide bonds of keratin, weakening the hair so it can be wiped away. The alkalinity helps swell the hair and speeds the reaction.
Step 2: The others don't fit — hydrogen peroxide is an oxidizing (bleaching) agent, sodium lauryl sulfate is just a surfactant/cleanser, and aluminum chlorohydrate is an antiperspirant. None of these reduce keratin disulfide bonds.
Answer: Option (3) — Calcium thioglycolate is the alkaline depilatory agent that breaks the −S−S− bonds of hair keratin. (3)
Depilatories are cosmetic products that remove unwanted hair by chemically dissolving it. Hair is made of keratin, a tough protein held together largely by disulfide (−S−S−) bonds. To break the hair, the depilatory must reduce and cleave these disulfide bridges.
Step 1: Thioglycolate salts are the standard reducing agents for this job. Calcium thioglycolate, used under alkaline conditions, breaks the disulfide bonds of keratin, weakening the hair so it can be wiped away. The alkalinity helps swell the hair and speeds the reaction.
Step 2: The others don't fit — hydrogen peroxide is an oxidizing (bleaching) agent, sodium lauryl sulfate is just a surfactant/cleanser, and aluminum chlorohydrate is an antiperspirant. None of these reduce keratin disulfide bonds.
Answer: Option (3) — Calcium thioglycolate is the alkaline depilatory agent that breaks the −S−S− bonds of hair keratin. (3)
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