Question

Using very little soap while washing clothes, does not serve the purpose of cleaning of clothes, because:

• A. soap particles remain floating in water as ions.
• B. the hydrophobic part of soap is not able to take away grease.
• C. the micelles are not formed due to concentration of soap, below its CMC value.
• D. colloidal structure of soap in water is completely distributed.

Answer 1

The Correct Option is C

The question is asking why using very little soap does not effectively clean clothes. To answer this, let's explore the concept of soap, its action, and the role of concentration in cleaning:

Understanding Soap and Its Action:

Soap molecules have two distinct ends:

• A hydrophobic (water-repelling) tail, which is non-polar and tends to attach to grease and dirt.
• A hydrophilic (water-attracting) head, which is polar and dissolves in water.

During cleaning, soap molecules arrange themselves in structures called micelles. In micelles, the hydrophobic tails encase greasy dirt, while the hydrophilic heads make contact with water, thus allowing the grease to be rinsed away.

Critical Micelle Concentration (CMC):

The formation of micelles only occurs above a specific concentration known as the Critical Micelle Concentration (CMC). If the soap concentration in water is below this value, micelles cannot form effectively.

Given this understanding, let's evaluate the options:

• Option A: "Soap particles remain floating in water as ions." - This is incorrect because soap needs to form micelles to clean effectively.
• Option B: "The hydrophobic part of soap is not able to take away grease." - Incorrect as the hydrophobic part works when micelles are formed.
• Option C (Correct Answer): "The micelles are not formed due to concentration of soap, below its CMC value." - Correct, because insufficient soap leads to an inability to form micelles.
• Option D: "Colloidal structure of soap in water is completely distributed." - Incorrect, as the colloids (micelles) need to form, not distribute completely beyond the CMC.

Conclusion:

The correct answer is that using too little soap results in a concentration below the CMC, preventing the formation of micelles, which are essential for cleaning clothes effectively.