question_answer 82)

  Water molecule is very polar. Polar end of molecule attracts opposite charges on another water molecule (acts like magnet). How will you explain this property of water with reference to upward movement of water? Comment on the upward movement of water given the intermolecular hydrogen bonding in water.

Answer:

                  Attraction of water molecules to polar surfaces describes the adhesive properties of water. Besides, the cohesive properties include the attraction between water molecules. These two cohesive and adhesive properties contributes and help in the upward movement of water by providing. (i)   High tensile strength                               Capability to resist a pulling force, i.e., gravitational force. (ii)  .High capillarity                          Ability to rise in thin tubes or columns, i.e., of tracheid sand vessels.            The intermolecular hydrogen bonding in water ensures that more water molecules areattraction to each other in liquid state than in the gaseous state. This contributes to surfacetension which in turn accounts for high capillarity in the xylem column.