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In many educational systems, especially those following a standard curriculum, students in Class 12 have a combination of main subjects and sometimes an additional subject. In your case, you have five subjects: Physics, Chemistry, Biology, Mathematics, and English. Here's how they typically categorize:

1. Physics - Main subject
2. Chemistry - Main subject
3. Biology - Main subject
4. Mathematics - Main subject
5. English - Usually a compulsory main subject

Usually, all five subjects are considered main subjects, especially in science streams. However, in some boards or schools, students can opt to have one of these as an additional subject. The additional subject often serves as a backup and is not mandatory to pass for overall qualification.