The lowest allowable energy state of an atom is called its:

• A. ionized state
• B. ground state
• C. valence state
• D. excited state

Answer: (B)

Verified step by step guidance

1. Understand that the problem is asking for the name of the lowest energy state of an atom.
2. Recall that atoms have discrete energy levels, and the lowest energy level is the most stable and least energetic state the atom can occupy.
3. Recognize that the term 'ionized state' refers to an atom that has lost or gained electrons, which is not the lowest energy state.
4. Know that the 'excited state' refers to any energy level higher than the lowest energy state, so it is not the correct answer.
5. Identify that the 'ground state' is the term used to describe the lowest allowable energy state of an atom.