Action of soap is due to emulsification and micelle formation, Comment .

Explanation

Soap molecule has two parts : Hydrophobic and hydrophilic. The first one attaches with oily dirt and the second attaches with water.

(a) Fig. (a) Arrangement of stearate ions on the surface of water at low concentrations of soap (b) Arrangement of stearate ions inside the bulk of water (ionic micelle) at critical micelle concentrations of soap.
As the dirty cloth is agitated in soap solution, several soap molecules arrange themselves radially, each attached with oil at one end and water on the other end. So, dirt is removed from the cloth and an emulsion of oily dirt and water is formed in the soap solution. Thus, soap helps in emulsification and washing away of oily dirt from the cloth.

Fig. (a) Grease on cloth (b) Stearate ion arranging around the grease droplet and (c) Grease due.