Energy level is Energy level.

The second principle energy level is the energy level that comes after the first principle energy level. The second energy level is farther from the atomic nucleus and contains the 2s and 2p sublevels.

The outermost principle energy level for strontium is the 5th energy level.

Carbon has four electrons in the outermost energy level, which is energy level two. It needs eight electrons to have this energy level filled.

The answer to this question is that the oxidation number for the 2nd energy level is +2. This is because the 2nd energy level is the second highest energy level in an atom, and thus has a higher oxidation number than the 1st energy level. The oxidation number for the 2nd energy level is determined by the number of electrons in the 2nd energy level.