Using very little soap while washing clothes, does not serve the purpose of cleaning of clothes, because:
soap particles remain floating in water as ions.
the hydrophobic part of soap is not able to take away grease.
the micelles are not formed due to concentration of soap, below its CMC value.
colloidal structure of soap in water is completely disturbed.
Cleansing action of Soap is due to micelle formation. If the concentration of Soap is very little, the micelles will not be formed as there is a requirement of a minimum concentration of soap for micelle formation called as the critical micelle concentration(CMC).
Hence, the answer is Option (3)
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