in

Also correct and probably more commonly spoken in England would be :- Pass algebra exam.

http://www.differencebetween.net/language/difference-between-in-and-on/ This website should help you with this question. You will use "in". Here are a couple examples. You can pass an exam in Algebra. You got five questions correct on your Algebra test. You really just have to memorize how you use these prepositions in English. It is difficult even for Native Speakers to differentiate the two. If you have any other questions, then message me. :)