Hemanth, only previous question papers will never be enough. Because they never include the entire syllabus. Even if you go back as many as 32 years, there might be still few topics left unasked. And if you miss that during preparation, you miss scoring. We have a list of books compiled for you:

Physics:

NCERT Physics Class XI & Class XII
Concepts of Physics by H. C. Verma
Objective Physics By DC Pandey
Fundamentals of Physics by Halliday, Resnick and Walker
Fundamental Physics by Pradeep
Problems in General Physics by IE Irodov

Chemistry:

NCERT Chemistry textbooks for Class XI and XII
Physical Chemistry by OP Tandon
ABC of Chemistry for Classes 11 and 12 by Modern
Concise Inorganic Chemistry by JD Lee
Dinesh Chemistry Guide
Practise books by VK Jaiswal, MS Chauhan and N Awasthi

Biology:

NCERT Biology Class XI and Class XII textbooks
Biology Vol 1 and Vol 2 by Trueman
Objective Biology by Dinesh
Objective Botany by Ansari
Pradeep Guide on Biology
GR Bathla publications for Biology

Now due to the lockdown, you might not have access to these books atleast until April 15th. So stick to NCERT books without skipping anything. Also if you are looking to prepare for NEET, we also have NEET Knockout packages.help you with your NEET preparation, we have NEET Knockout packages that you can check at: https://learn.careers360.com/knockout-neet-may/ .