A molecule in which centre of gravity of positive nuclei and revolving electrons do not coincide is

A molecule in which centre of gravity of positive nuclei and revolving electrons coincide is

In non-polar molecules, centre of gravity of positive nuclei and revolving electrons

Under which condition (i) the centre of buoyancy coincides with the center of gravity (ii) the centre of bouyancy does not coincide with the centre of gravity.

Does centre of mass and centre of gravity body always coincide?

Does centre of mass and centre of gravity body always coincide?