Question

Cohesive force of water molecules is of the magnitude of
A) 1-10 atm
B) 10 -15 atm
C) 45 - 200 atm
D) 15 -45 atm

Answer 1

Hint:Let us first understand what is meant by cohesive force. Cohesive force is the attractive force between the same type of molecules. It can also be called a collective intramolecular force.

Complete answer:
 In water, hydrogen bonds are held together by the cohesive force that creates a surface tension. The cohesive force of about 47- 207 atm is required to drive water or sap into xylem elements or tracheary elements or to meet the transpiration pull such that the water column is not harmed.

Additional information: Water is considered as the most cohesive liquid. Water is easily attracted to other molecules. Adhesive force pulls water molecules towards the other molecules.Attractive force between the different molecules is called the adhesive force. The light weighted objects float on water due to the surface tension that is created on water by cohesive force. For example, certain insects can walk on water without sinking due to cohesive force and water droplets stay on the flower petals and leaves are due to adhesive force.

Therefore the correct answer is option (C)45-200 atm.

Note:Remember that cohesive force is maximum in solid state and minimum in gaseous state. Cohesion is also responsible for water's high boiling point that helps the animals to regulate their body temperature. Plants take up water at their roots because of the cohesive force of water molecules.