The term nucleus is used to describe the center of something, usually an atom or a cell; it could be used to describe the center of a city as well.
City hall
in the nucleus
in the nucleus of a cell
In the nucleus.
You can find a proton in the nucleus of the atom along with neutrons.
only eukaryotic cells have a nucleus if it is prokaryotic cells don't have nuclei
If I understand your question correctly, then it would be the mayor.
the nucleus
outside the nucleus in the electron cloud
all cells have a necleus because it is what controlls the cell.
the comma the nucleus and the tail
both