Can a metal be used as a medium for a dielectric?

Explain the polarization of a nonpolar molecule in a uniform electric field and define linear isotropic dielectrics.

The dielectric constant of pure water is $81$. Its permittivity will be:

On what does the extent of polarization depend?

What are polar molecules and non-polar molecules? Give examples of both.

Assertion : In the absence of an external electric field,the dipole moment per unit volume of a polar dielectric is zero.
Reason : The dipoles of a polar dielectric are randomly oriented.