My evergreen recommendations for science books in Class XI and XII are NCERT books which you can download from their site for free, or buy from a nearby bookstore. Not everyone believes in this recommendation though – for some these books are too brief and cryptic.
Here are some of the books that I used when I was a student almost 30 years ago, and I find that they are still the favorites!
Fundamentals of Physics, by Resnick, Halliday
A remarkable book, and if you have to choose only one book to study from, this is the one. When I studied (1990-91), it was a thin book, now it weighs more than 5Kgs!
Problems in General Physics, by I E Irodov
A great collection of really tough physics questions. You can also find solutions book for this, which can be a good companion book. When I was studying, this book was a craze, and people who used to regularly quote from this book a question they had solved, were considered genius!
Plane Trigonometry, by S.L.Loney
Coordinate Geomtry, by S.L. Loni
Mechanics and Probability, by Bostock and Chandler
Advanced Organic Chemistry, by Bahl and Bahl
Recommendations from a friend
A problem book in mathematical analysis, by G N Berman
Problems in Mathematics: with hints and solution, by Govorov et.al.
Science For Everyone: Aptitude Test: Problems In Physics
University Chemistry, by Bruce H Mahan
Organic Chemistry, by Morrison and Boyd
Concise Inorganic Chemistry, by J D Lee
Concepts of Physics – Part 1 and 2 – by H C Verma
Problems in Calculus of One Variable, by Maron