Question six is now a smidge inaccurate. When they were first introduced and passed by Congress, there were twelve amendments in the Bill of Rights. The first 10 amendments that everybody knows as the Bill of Rights passed pretty much immediately by enough States so they were ratified right away.
However, one of the other two was just finally ratified by the necessary majority of States a few years ago and became the 27th Amendment to the Constitution. It didn't have a seven year clause built into it, so it was able to hang in limbo for over 200 years. So, in actuality, the Bill of Rights are Amendments 1-10, and 27.
EDIT: You answered 95% of questions correctly. Here's your rating:
0-20%: Maybe you're still thinking too much about the Old Country -- and that's where you should probably be.
25-40%: Mmmm. Do you really want to be a citizen? This kind of performance isn't going to impress those nice immigration folks.
45-60%: Not too bad, but you really need to break out the civics books again -- word is, the INS is looking for an 80 percent score.
65-80%: Hey, you may make a good citizen yet! Look at your wrong answers and a little revision should do the trick.
85-100%: Welcome to the United States! (And, truth be told, you know more about this great land than most Americans.)
I missed number 19 about which INS form is used by naturalized citizens.