The unit of polarizability of the molecule is . . . . . . .

If the dielectric constant and dielectric strength are represented by $k$ and $x$ respectively,what properties should a suitable material have to be used as a dielectric in a capacitor?

The electric force acting between two point charges kept at a certain distance in vacuum is $16 \ N$. If the same two charges are kept at the same distance in a medium of dielectric constant $8$,the electric force acting between them is . . . . . . .

Why can a metal not be used as a dielectric in a capacitor?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: Net dipole moment of a polar dielectric substance is zero in the absence of an external electric field.
Reason $(R)$: In the absence of an external electric field,the different permanent dipoles of a polar dielectric substance are oriented in random directions.
In the light of the above statements,choose the most appropriate answer from the options given below.

If the dielectric constant of a substance is $K = \frac{4}{3}$,then the electric susceptibility $\chi_{e}$ is