Dimensions of charge are

If $e$ is the electronic charge,$c$ is the speed of light in free space,and $h$ is Planck's constant,the quantity $\frac{1}{4 \pi \varepsilon_{0}} \frac{| e |^{2}}{h c}$ has dimensions of .......

Let $x = \pi R \left( \frac{P^2 - Q^2}{2} \right)$,where $P, Q$ and $R$ are lengths. The physical quantity $x$ is

Dimensional formula for torque is

Out of the following pairs,which one does not have identical dimensions?

The dimensional formula of $\varepsilon_r$ is .......