Hi nitinkrsri,
I really don't think they will ask that question.
In my opinion, it is not reasonable to require you to remember all the 13 states.
I did not remember them all before interview:
http://www.immigrationportal.com/showpost.php?p=1847114&postcount=2853
Another question I was asked was about the bill of rights and immediately after I said "freedom of speech" my interviewer stopped me from giving more answers. He said "that's enough".
If someone has been asked to state all 13 colonies, please report. I really doubt that.
But then it is their interview and they can ask whatever they want; so don't blame me if they indeed ask this question.
One of my friends told me he got about 4 questions wrong because he did not study at all (what a brave person!), but he still passed.
So, read the Q&A in the booklet one more time before you go to bed tonight, and relax, you'll be fine.
More than brave I would say "foolish" I believe at the time I was preparing for my interview and I mentioned about memorizing the 13 colonies someone mentioned that they were asked for them. Anyway, I might be wrong. Yes, most interviewees don't mention having been asked this question, which makes me believe it is not a commonly asked question. The IO would have to keep track of all the states you are saying and making sure you don't repeat or miss any.