Question

An example of physical quantity having no unit is_______________________

Answer 1

unit-less physical quantities are those in which by taking their formula their constituent units in numerator and denominator gets cancelled.

Example

= No.of mole of X/No.mole of X+No. of moles of Y

                             =Moles/Moles===:> no unit!!

Other examples

Strain

refractive index

specific heat