Question

As temperature of water increases, its viscosity
A.Remains unchanged
B.Decreases
C.Increases
D.Increase or decrease depending on the external pressure

Answer 1

We first need to know that the resistance of a fluid to gradual deformation by shear or tensile stress is characterised as viscosity. To put it another way, viscosity refers to a fluid's resistance to flow. For our understanding, honey is thicker than water and, as a result, it means that honey is more viscous than water. A fluid's viscosity is a measurement of its resistance to deformation at a specific rate.

Complete answer:
We must have to know that temperature affects the viscosity of water. At lower temperatures, water has a higher viscosity, whereas at higher temperatures, it has a lower viscosity. The energy released by higher temperature causes molecules to move at a quicker rate, eventually overcoming the bonds or binding forces between them. This reduces the viscosity of the liquid, making it more fluid.
At lower temperatures, the water molecules have less kinetic energy to move, causing the water to flow more slowly (and eventually convert to ice), and the kinetic energy increases as the temperature rises. It also impacts its molecular structure.

Thus, the correct option is B.

Note:
We can note the fact that the term "ideal" or "inviscid" refers to a fluid that has no resistance to shear stress. In superfluids, zero viscosity is only observed at extremely low temperatures. Otherwise, the second law of thermodynamics mandates that all fluids have positive viscosity; such fluids are called viscous or viscid in technical terms. Pitch, for example, may appear to be solid due to its high viscosity.