Hello Aspirant

You can find all the previous year's question papers on your respective Board of Examinations website, they provide all the information ranging from registration number, timetable, tentative dates, repeat examination, results, and also the previous year's question papers there.

For the CBSE Board, here's the link for all the question papers, just select your class and the subject- https://www.cbse.gov.in/cbsenew/question-paper.html

Here's a link to PW's website where they have linked all the previous year's question paper- https://www.pw.live/exams/school/isc-class-12-previous-year-question-papers/ Hope this helps