$A$ dimensionless quantity

The $SI$ unit of a physical quantity is pascal-second. The dimensional formula of this quantity will be ..............

The dimensions of ${e^2}/(4\pi \varepsilon _0 hc)$,where $e, \varepsilon _0, h,$ and $c$ are electronic charge,electric permittivity,Planck's constant,and velocity of light in vacuum respectively,are:

Dimensions of the following three quantities are the same:

The dimension of electric current is

If $\varepsilon_0$ and $\mu_0$ represent the permittivity and permeability of free space respectively, then the dimension of the product $\varepsilon_0 \mu_0$ is,