Synthesized answer
The provided passage does not contain information about what questions remain unanswered. It only states the title of the work, the author, the categories it falls under, and the page number [146]. Therefore, I cannot answer what questions remain unanswered based on this information.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: On the Constitution of Atoms and Molecules by Niels Bohr Categories: Atomic theory Pages: 146