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JEE Main levelSingle correct optionDifficulty 2 of 3sc125

Which of the following statements about soap micelles in water is correct?

  1. AMicelles form only above the critical micelle concentration and above the Krafft temperature
  2. BThe hydrocarbon tails of the soap anions point towards the water and the ionic heads towards the centre
  3. CMicelles form at any concentration of soap, however low
  4. DA micelle is a true molecular solution with a size below 1 nm

Answer: A

A soap such as sodium stearate aggregates into micelles only when its concentration exceeds the CMC and the temperature is above the Krafft temperature. In a micelle the hydrocarbon tails are in the interior, away from water, and the ionic heads face the water. Micelles are 1-100 nm aggregates, so they are colloidal.
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