Because it dissolves glass, chemists have traditionally....

sorry, where is the question?

Princeton - SC

Because it dissolves glass, and so chemists have traditionally been forced to store hydrofluoric acid in lead containers.

a) and so chemists have traditionally been forced to store hydrofluoric acid in
b) so therefore chemists have been forced to store hydrofluoric acid traditionally in
c) so chemists have been forced to store hydrofluoric acid traditionally in
d) chemists have been forced to store hydrofluoric acid in traditionally
e) chemists have traditionally been forced to store hydrofluoric acid in

OA is E

At first glance the sentence does seem to violate the "opening modifier" rule. But all the choices have the same "problem". Thus if this was an actual problem on the exam you would simply ignore that because its not a split. Use that as part of your process; if all the answer choices make the same "mistake", its not actually a mistake.

At any rate, a couple of ways to look at this.

INTUITIVE
"It" refers unambiguously to hydrofluoric acid (make sure you understand why). Now reread the sentence with "it" replaced by "hydrofluoric acid". You get "Because hydrofluoric acid dissolves glass, chemists have...". Does that sound better? You could also flip the sentence, putting the modifier at the end and the sentence seems to still make sense.

GRAMMATICAL
Modifiers headed with "because" actually modify a verb (or clause) rather than a noun. A lot of the opening modifiers in GMAT problems are intended to modify a noun and the noun must directly follow the modifier, as in "Tired out from playing basketball, David decided to take a nap." Note that you cannot flip that sentence; it sounds ridiculous because "Tired out..." would modify "nap".