Answer is: C is equal to 2, D is equal to 6 and E is equal to 1.
C, D and E represent number of electrons on each atomic orbital in sodium atom.
Electron configuration of sodium atom: ₁₁Na 1s² 2s² 2p⁶ 3s¹.
Atomic number of sodium is 11, it means that it has 11 protons and 11 electrons, so atom of sodium is neutral.
