Synthesized answer
The provided passage does not contain information about what questions remain unanswered in the book "Mysticism and Logic and Other Essays" by Bertrand Russell. The passage only includes the title, author, and category of the work. Therefore, it is not possible to answer the question using the given text.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Mysticism and Logic by Bertrand Russell Categories: Mathematics Pages: 256