DS has this one:

http://www.boydsmillspress.com/books/nonfiction/highlights_book_of_science_que.html

and another one called The Big Book of How, What, and Why. Here are a couple of other titles that seem similar...

http://search.barnesandnoble.com/Ho...tm=1&usri=science+questions+kids+ask

http://search.barnesandnoble.com/Wh...m=12&usri=science+questions+kids+ask

Just check the kids section of a bookstore (or heck, maybe even a library has some of them) and you'll find lots of these types.

Good luck.