Final answer:
The coefficient of friction is the physical quantity with neither dimensions nor units. It is dimensionless because it's the ratio of two forces. Force, in contrast, is a vector quantity with both magnitude and direction as its characteristics. The correct option is C. coefficient of friction.
Step-by-step explanation:
The physical quantity that has neither dimensions nor unit among the given options is coefficient of friction (option C). This is because the coefficient of friction is a dimensionless quantity which is a ratio of two forces and thus does not require a unit for its expression.
On the other hand, angle (option A) is also dimensionless, but its units are often expressed in radians or degrees. Luminous intensity (option B) is a base physical quantity with a unit, candela. And current (option D) is also a fundamental physical quantity measured in amperes.
Regarding the type of physical quantity force is, force is a vector quantity (option b) because it has magnitude as well as direction. This characteristic distinguishes it from scalar quantities, which only have magnitude. For example, centripetal acceleration is a vector quantity because it has both magnitude and direction (option d), making it a concept described by dynamics rather than kinematics alone.
Physical quantities can be expressed as combinations of the four fundamental physical quantities: length, mass, time, and electric current. Other physical quantities, such as luminous intensity, temperature, and amount of a substance, are also fundamental but are not part of this specific combination.
The correct option is C. coefficient of friction.