Student or Learner
I have never appeared in any exam with so many subjects.
There are many exams in which we have to appear for multiple subjects, in that case is it ok to say 'exam with so many subjects'. This exam might have science, English, Mathematics, Geography and some other subjects
I have never taken an exam that covered so many subjects.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.