Explanation:

Surface tension is defined as the force acting per unit length perpendicular to an imaginary line drawn on the surface of the liquid, tangential to the surface. This force is developed due to the molecular forces of attraction between the molecules of the liquid itself.

Cohesion:
Cohesion refers to the force of attraction that exists between the molecules of the same substance. In the case of a liquid, the molecules at the surface of the liquid are attracted to the molecules beneath them by cohesive forces. Because of this, the molecules at the surface of the liquid tend to be pulled inward, causing the surface to contract.

Adhesion:
Adhesion, on the other hand, refers to the force of attraction that exists between the molecules of different substances. In the case of a liquid in contact with a solid, the molecules of the liquid are attracted to the molecules on the surface of the solid. This results in the liquid being pulled up the surface of the solid, creating a meniscus.

Surface Tension:
Surface tension arises because the cohesive forces between the molecules at the surface of the liquid are stronger than the adhesive forces between the liquid and the container. This causes the surface of the liquid to behave as if it were a stretched membrane. The molecules at the surface of the liquid are pulled inward, causing the surface to contract and minimizing its surface area. This is why liquid droplets tend to be spherical in shape.

Conclusion:
In conclusion, surface tension is due to the cohesive forces between the molecules at the surface of the liquid. These forces cause the surface of the liquid to behave as if it were a stretched membrane, resulting in the contraction of the surface and the formation of a spherical shape for liquid droplets.