Which of the following questions was left unanswered by Rutherford's atomic model?

• A. Is the atom mostly empty space?
• B. Are most alpha particles undeflected when passing through gold foil?
• C. Does the atom contain a dense, positively charged nucleus?
• D. How are electrons arranged around the nucleus?

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the context of Rutherford's atomic model, which was developed based on the gold foil experiment. This model proposed that atoms have a small, dense, positively charged nucleus and that most of the atom's volume is empty space.
2. Step 2: Identify the questions that Rutherford's model successfully answered: (a) The atom is mostly empty space, (b) Most alpha particles pass through undeflected, and (c) The atom contains a dense, positively charged nucleus.
3. Step 3: Recognize that Rutherford's model did not explain the arrangement or behavior of electrons around the nucleus, which was a significant limitation of the model.
4. Step 4: Understand that the question 'How are electrons arranged around the nucleus?' remained unanswered by Rutherford's model and was later addressed by the Bohr model and quantum mechanics.
5. Step 5: Conclude that the correct answer to the problem is the question about electron arrangement, as it highlights the key gap in Rutherford's atomic theory.