Hi Ragul,

See, you are students of class 12th. If you are from CBSE board, studying your textbook  thoroughly will help you score good marks, but that's never enough. If you have completed your textbook thoroughly I would suggest you to solve sample question papers because even though you know the answer you might not be able to answer it because of confusion. So you must practice sample questions and go through some other books if time permits.

Hopefully this serves your query.

Comment below for any more queries.