Marylaine posted a link to the United States Citizenship and Immigration Services website, which has a .pdf of typical questions found on the naturalization exam.
(Hey, Keem found the newest version of the exam!)
Some of the questions I knew (What are the colors of our flag?), some were hard (Why are there 100 senators in the US Senate?), and some I can’t imagine answering in a way that is easily quantified (Who is Martin Luther King, Jr.?).
Go check it out!