does all questions in up board 12th exam come from back exercise in chemistry and back exercise is enough to score 60+ in up board
hope you are doing good.
as far as the 12th class NCERT book is concerned it is sufficient to have NCERT. but thorough go through is required, not only back exercise is sufficient but between in text are also important. NCERT is self sufficient
Intext questions and back exercise are very important in board exams. As most of the numericals come from that. If you refer ncert books it'll be good for you. As it not only will be useful for boards but also entrance exams. You can also see previous years question papers most of the common questions repeat each year.
Yes you can score 60+ if you practice all the questions from your book. If you want more go for ncert, solve question papers.
Hope it helps.