Question

why viscosity is an intensive property

Answer 1

Because viscosity is resisting force per unit area

An average force will be defined for each unit area

Hence if we take viscosity of an unit area we get the same magnitude

Hence viscosity is an intensive property

Answer 2

The properties like temperature, density, hardness, refractive index, pressure, melting or boiling point do not depend on the amount of material in the system. We call them as Intensive Properties. ... We call them asExtensive Properties. Now think about viscosity and color.