What structure separates the contents of the nucleus from the cytoplasm

Nuclear Membrane separates the contents of nucleus from the cytoplasm.

Explanation:

Two nuclear membranes form a nuclear envelope that separates the nuclear contents from the cytoplasmic content of the cell.These run continuous with the endoplasmic reticulum  enclose a perinuclear space in between them.The nuclear membrane contain nuclear pore that control exit and entrance of molecules coming in and leaving the nucleus.

the atomic number of magnesium is 12. its nucleus must contain 12 protons and no electrons. the atomic number of an atom is determined by the number of protons.

magnesium is an electrolyte injection commonly used to treat low magnesium levels in your blood. it is also used to prevent or control seizures in women with preeclampsia or eclampsia.