Hey!

KVPY is kind of highly competitive and tough exam, but it gives greater value in future. while preparing for such exams, you will have to thorough the basics before attempting the question paper. so, 1st prepare the best with NCERT books and some of your 1st yr UG books. after which you have to move to previous year papers.

if you are already thorough with the basic content, then previous year papers are the holiest thing you can study with. but without basics, you wont get anything out of it.

so with basics if you do prev yr papers, you will get the maximum marks. (atleast 80-90%) but without basics and only prev yr papers will help only up to 60 or 70 %