Nitrogen (N) has seven electrons. How many electrons are in the second shell of a nitrogen atom?

Five electrons

Explanation:

Nitrogen has 7 electrons - - - 2 in the first shell, and 5 in the second shell (so five valence electrons). Oxygen has 8 electrons - - - 2 in the first shell, and 6 in the second shell (so six valence electrons).

5

Explanation:

The first shell of an atom always contains 2 electrons, every other shell can contain up to 8 electrons each.