Question

define viscosity and what is its SI unit​

Answer 1

$\huge\underline\green{Answer:-}$

viscosity is the quantity that describes a fluid's resistance to flow. Fluids resist the relative motion of immersed objects through them as well as to the motion of layers with differing velocities within them. The SI unit of viscosity is the pascal second [Pa s], which has no special name.

Answer 2

Answer:

Viscosity is a property of liquids that is closely related to the resistance to flow.

It is defined in terms of the force required to move one plane surface continuously past another under specified steady-state conditions when the space between filled by the liquid in question.

Its SI unit is Pascal.