Can anyone give me a link for free download of modern ABC chemistry books in PDF form?
It can't be downloaded from any website for free, You can purchase it from any book store or online. If you are preparing for NEET Entrance Exam then firstly I would suggest you to complete NCERT books as it will help you to clear your basics then you can prefer other books. The other books you can prefer below given:
Physics
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
Physical Chemistry by OP Tandon
Chemistry
ABC of Chemistry for Classes 11 and 12 by Modern
Concise Inorganic Chemistry by JD Lee
Dinesh Chemistry Guide
Biology
Biology Vol 1 and Vol 2 by Trueman
Objective Biology by Dinesh
Objective Botany by Ansari
Pradeep Guide on Biology
Good Luck!