Question

The critical micelle concentration (CMC) of a soap solution is \( 5 \times 10^{-4} \, \text{mol L}^{-1} \). Identify the correct statements about this solution.
[I.] The micelle is stable if the soap solution concentration is \( 10^{-7} \, \text{mol L}^{-1} \)
[II.] The micelle is stable if the soap solution concentration is higher than \( 5 \times 10^{-4} \, \text{mol L}^{-1} \)
[III.] Micelles are also known as associated colloids.

• A. I, II, III
• B. I, II only
• C. I, III only
• D. II, III only

Hint:

Micelles form only when the concentration of soap exceeds the CMC value. Below this threshold, they exist as simple molecules and not as colloidal aggregates.

Answer 1

The Correct Option is D

Step 1: Evaluate the statements

• Statement I is incorrect: Micelles do not form if the concentration is below the CMC (i.e., at \(10^{-7} \, \text{mol L}^{-1}\), which is much lower than the given CMC).
• Statement II is correct: Micelles form and are stable only when the concentration is above the CMC.
• Statement III is correct: Micelles are indeed classified as associated colloids due to their structure and behavior.

Final Answer:

II, III only