Question

Moist soil grains are pulled together because surface area of thin film of water is reduced .what does this sentance surface area of thin film of water is reduced means ??? Can you explain me clearly and in detail please .

Answer 1

It means that there is thin water films are present in between these moist soils grains. So these films have surfaces. So these surfaces also show surface phenomenon like surfaces tension. Which means the surface will try reduce its surface area. So there will be a force on these grains and the grains will move closer as surface trys to reduce its area. So thereby the soil grains will be pulled together.