The first, second, and third shells and the 4s subshell of an atom are filled. How many electrons are present in the atom? What is the identity of the element?

• A. The atom contains 30 electrons.
  The element is Zinc.
• B. The atom contains 29 electrons.
  The element is Copper.
• C. The atom contains 28 electrons.
  The element is Nickel.
• D. The atom contains 27 electrons.
  The element is Cobalt.

Answer: (A)