is cengage and arihant are the best series to prepare for neet 2020 or not please suggest me thank you................

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Physcis  Best Books:

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 Best Books:

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 Awasth

Biology Best Books:

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

Yes, both these books play major role for preparation of neet, arihant publication has some good books for neet and solved previous years paper of arihant are very helpful for the preparation. In chemistry physical chemistry of cengage publication is good book. For physics you can take arihant publication but I advice you for HC verma concept of physics. For bio you can take arihant