which book is best for BITSAT ----sample paper or mock tests or any book with study material or what and of which publication

In order to crack BITSAT make sure your concepts are clear. You can take help of NCERT books for that. You should complete NCERT book first for your preparation the you can opt for other books. BITSAT is all about speed. So, you should solve as many as mock test series for your practice. You should refer previous year papers as well to know the exam pattern and to understand the level of questions.

Below are the recommended books for your preparation

General/All-in-One Books

-A Complete Success Package for BITSAT by Arihant (with CD)

-Comprehensive Guide to BITSAT with Mock Test CD (with Insta Reports and sync facility) by Disha Experts

Other Reference Books

1. The Pearson Complete Guide to BITSAT
2. Comprehensive Guide to BITSAT Online Test with Past Papers from 2005-2016 Solved Papers & 5 Mock Online Tests
   
   Best Physics Books for BITSAT Exam

Concepts of Physics by H. C Verma Vol 1 and Vol 2

Understanding Physics Series by D. C Pandey

Best Chemistry Books for BITSAT Exam

Physical Chemistry by P. Bahadur

Inorganic Chemistry by O. P. Tandon

Organic Chemistry by Arihant (Theory & Practice)

Best Maths Books for BITSAT Exam

Objective Mathematics by R. D. Sharma

Best English and Logical Reasoning Books for BITSAT

BITSAT English Proficiency and Logical Reasoning by Disha Experts

You can consider below details -

Physics -  Concepts of Physics by H. C Verma Vol 1 and Vol 2 Problems in General Physics by I.E. Irodov Arihant Physics by D. C. Pandey Advanced level Physics by Nelson and Parker Fundamentals of Physics Resnick, Halliday, Walker.

Chemistry - Atkins' Physical Chemistry Physical Chemistry by N Awasthi Organic Chemistry by Paula Bruice Yurkanis Organic Chemistry by M.S. Chuahan Inorganic Chemistry by J.D.Lee Inorganic Chemistry by O.P.Tandon.

Mathematics - Higher Algebra by Hall Knight+ Bernard-child Differential Calculus by Arihant Integral Calculus by Arihant Problems in Calculus of One Variable Algebra by I.A.Maron Class XI & XII by R.D. Sharma.

(a) English Proficiency (b) Logical Reasoning

BITSAT English Proficiency & Logical Reasoning by Disha Experts The Pearson Complete Guide to the BITSAT (English) by One Learn Education Wren and Martin.

You can download the sample papers below -

BITSAT Sample Papers

To get the complete preparation tips, you can go throug the below article -

How to prepare for BITSAT 2018

Hope this helps!!!!