Finding the identity of an unknown acid?

Question

Your roommate made a slippery mess of soap all over the place, so you plan to neutralize it with acid. You grab a beaker with 16.3 grams of a STRONG ACID, but when you get to your bathroom, you've forgotten what kind of acid it is and worry about it eating through the pipes.
Naturally you test it to find that:
1) adding a Pb 2+ solution yields a precipitate
2) titrating with 201.5 mL of 1.00 M NaOH neutralizes the acid.

Which strong acid did you pick?
a) HF
b) HCl
c) HBr
d) HI
e) HNO3

I know that it isn't going to be HF because it is a weak acid, and I know that it won't be HNO3 because Nitrates are soluble. So it has to be HCl, HBr, or HI because the all form precipitates with Pb 2+. I just don't know how to use the titration data to deduce the identity of the acid.

Answer 1

Let the acid be called A. Let the NaOH solution be called NS.

16.3gA/201.5mLNS x 1000mLNS/1.00molNaOH x 1molA/1molNaOH = 80.9g A per 1 mole A

It must be HBr, because 79.9 + 1 = 80.9, the molecular weight of HBr.