The fundamental physical quantities that have the same dimensions in the dimensional formulae of torque and angular momentum are

Out of the following four dimensional quantities,which one is called a dimensional constant?

The electrical resistance $R$ of a conductor of length $l$ and area of cross-section $a$ is given by $R = \frac{\rho l}{a}$,where $\rho$ is the electrical resistivity. What is the dimensional formula for electrical conductivity $\sigma$,which is the reciprocal of resistivity?

The quantities $A$ and $B$ are related by the relation $m = A/B$,where $m$ is the linear density and $A$ is the force. The dimensions of $B$ are of

Write the dimensional formula and dimensional equation of density.

The dimension of $\sqrt{\frac{\mu_0}{\varepsilon_0}}$ is the same as: