Final answer:
Without additional context for 'peak E,' it's impossible to accurately determine the number of electrons; however, for nitrogen with an atomic number of seven, it has two electron shells as per electron configuration principles.
Step-by-step explanation:
The question appears to be referring to the quantum model of an atom, where electrons can occupy various energy levels or shells. The peak 'E' likely refers to a specific energy level within an atom. However, without additional context, such as a graph or diagram indicating what 'peak E' refers to, it is impossible to provide an accurate number of electrons in peak E. Normally, the number of electrons at any given energy level or shell can be determined using the quantum numbers and electron configuration rules or the provided context of a specific problem.
Nitrogen has an atomic number of seven, and according to the electron configuration principles, it has two electron shells, with the first shell (n=1) having 2 electrons and the second shell (n=2) having 5 electrons, for a total of 7 electrons. The answer to the example question would be 'b. two' for the number of electron shells in a nitrogen atom.
For further clarification, the electron configuration can be written out for elements such as Cd with 48 electrons and Mg with 12 electrons to understand how electrons are arranged in their respective shells, which will then also help to understand concepts like the maximum number of electrons that can occupy a shell or the number of electrons in specific orbital types.