Engineering Entrance Exam

Hi,
Following are the best books for chemistry:
Organic Chemistry by Morrison and Boyd for Organic Chemistry
Organic Chemistry by Solomons and Fryhle for Organic Chemistry
A Guidebook to Mechanism in Organic Chemistry by Peter Sykes for Organic Chemistry
This book must be read irrespective of whether you read 2 or 3. But, it is suggested that you read this book only after you have covered all or at least a large part of your organic chemistry syllabus.
Concise Inorganic Chemistry by J. D. Lee for Inorganic Chemistry
[Practice] Modern Approach to Chemical Calculations by RC Mukherjee
Following are the best books for mathematics:
The elements of coordinate geometry by S.L. Loney
Plane Trigonometry by S.L. Loney
Higher Algebra by Hall and Knight
(Do not use these three books for theory. They are quite old-fashioned.)
Problems in Calculus of One Variable by I.A. Maron
[Practice] Course in Mathematics for IIT-JEE by Tata McGraw Hill publications
Following are the best books for physics:
[Practice] Concepts of Physics by H. C. Verma
[Practice] Problems in General Physics by I. E. Irodov
This is generally of a level above the general questions asked currently in IIT-JEE and may be considered optional.
Fundamentals of Physics by Halliday, Resnick and Walker
Note that I have tried to create an exhaustive list. You are not expected to buy them all. However, it is important to solve problems from as many books as possible. On the contrary, it's better to read theory from say one or two books or at most three.
I hope this helps you.
All the best!