The earth's atmosphere is divided into five layers. in the middle layer is where most foreign objects, such as meteors, will burn up as they enter the atmosphere. a) exosphere b) mesosphere c) stratosphere d) troposphere

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.