I'm finding a lot of inconsistency with the solubility rules from different sources. especially when it comes to SO4(negative 2 charge). my teacher told me: soluble except when combined with Ca2+, Ba2+, Sr2+, Pb2+... however, other sources sometimes include Hg(II) 2+, and some Ag+, and some both Hg(I) and (II).... so confusing. any ideas? also... not as important, but what is the format of the AP test? I know its 75 MC and then 6 FRQs, but how much are the MC and FRQ sections scaled? And also, it seems that each FRQ varies in points?