pKa1 and pKa2 are the negative logs of the acidity constants for the first and second stage in which a polyprotic acid loses a proton. pKa(overall) is the negative log of the overall acidity constant for the overall ionization reaction of the polyprotic acid. For example, using H2CO3 as the polyprotic acid:

So, pKa1 and pKa2 only really matter when the problem is asking for second and first ionization? E.g. in problem 12.35, it simply asks for Ka value and gives a pKa1. I could just take 10^-pKa1 and get the answer? I do not have to worry about the 1 subscript?