It's fairly basic, occasionally repetitive, and because the book was published 50 odd years ago some of the content in here is out of date, but it's still an interesting - and I think successful - example of the science communication of the day. Particularly physics communication. (This was sold as a science book, but biology gets a grudging 10% of entries.) Nonetheless it's got a simple and well-organised structure. There are 100 basic questions, covering concepts like imaginary numbers, solar wind, the uncertainty principle and so forth, and each has a short, clear answer. It's obviously written for laypeople (these were originally a series of columns in a magazine), and so the language is simple and the analogies usefully non-technical. The example of people moving in a grid to illustrate the link between entropy and order, for instance, was particularly effective.