Question

which quantity has unit but no dimension??

Answer 1

Dimensionless quantity. In dimensional analysis, a dimensionless quantity is a quantity to which no physical dimension is applicable. It is also known as a bare number or a quantity of dimension one and the corresponding unit of measurement in the SI is one (or 1) unit and it is not explicitly shown.

Answer 2

Yes, a quantity can have unit but no dimension. These are Dimensionless Quantities, some of which have units. This would be things like angles, proportions, or ratios. An example would be an angle of one radian.