Why dont the nuclei have permanent electric dipole
moments; buthave only magnetic dipole moments, while the molecules
can have bothelectric and magnetic dipole moments?

Answer and explanation:

The nuclei don't have a permanent electric dipole because they have a positive homogeneous distributed net charge. The requirement for the existence of a permanent electric dipole is that the body has positive and negative charges distributed in an inhomogeneous way, where positive and negative charges are well-differentiated and incapable of mooving its relative position. This is exactly what happens with molecules.

Magnetic dipole moments are related to sub particle movement inside atomic particles. That's why nuclei and molecules have it.

the largest known star in the universe is uy scuti, a hypergiant with a radius around 1,700 times larger than the

scientific laws are the result of testing theories and proving them to be facts.