Question

With the help of a diagram explain cleansing action of soap.

Answer 1

soap has a tadpole like structure which has a hydrophobic(water repelling) tail and a hydrophilic(water attracting) head containing ionic element like sodium ...
when a cloth full of dirt and grease is dipped in a soapy water the hydrocarbon end reacts with the dirt and grease and dissolves into it whereas the ionic end dissolves in the water . 
thus the total charge of the chain becomes negative and they repel each other forming a  structure in which the dirt or grease is at the centre and the chain pointing outwards .
later when the cloth is rinsed the dirt along with the micelle comes out of the cloth inside the water which now appears dirty .
thus this is a cleansing action of soap.. 

soap doesn't work in hard water because in hard water mg and ca ions are present which reacts with the chain and does we need large amount of soap in hard water and many times ,it doesn't work in the hard water....

Answer 2

${\huge{\mathfrak{Answer:-}}}$

$<b><u>$Cleansing action of soaps:

The dirt present on clothes is organic in nature and insoluble in water. Therefore, it cannot be removed by only washing with water. When soap is dissolved in water, its hydrophobic ends attach themselves to the dirt and remove it from the cloth. Then, the molecules of soap arrange themselves in micelle formation and trap the dirt at the centre of the cluster. These micelles remain suspended in the water. Hence, the dust particles are easily rinsed away by water.