It depends upon how much you have gained and weather you know the concepts and theories.
Because if you go with beginning of the syllabus and all preparation than it is very hard to get 180+ marks in just 20 days.
Than it depends upon the luck .
Because in 20 days you can not cover all the syllabus and you can not do practice .
I hope you get my point
So good luck

you have a number of books in the market going by NCERT guidelines SL Arora is a good option since it will introduce you to all formulae and basic numericals associated with them
however you may also buy books like Arihant which will give you a good knowledge and practice of different numericals asked at the MCQ level based upon physics in NEET
however you have to keep a copy where you maintain all notes of important formula and their applications and glanced through it before your examinations on a daily basis

Level of difficult in bitsat exam is high it is thought to be one of the most difficult entrance exam for Engineering both on the level of questions and on the cutoff .

Dear Amit, all books available in the market are very similar in the nature of their content of study material but the important thing is what you make of it.

Here I can give you the list of books for each section that can help you accelerate your preparation to ace the tests.

CAT Books For Quantitative Ability:
1.NCERT mathematics books (from 6th to 10th class) ::
These books are a good way to start if one needs to clear their basics and concepts. NCERT books are best to start your CAT Preparation with only if you have a lot of time before your exam date and need to brush up on concepts before solving advanced problems.

2.How to Prepare for Quantitative Aptitude for the CAT (by Arun Sharma)
(publisher: Tata McGraw Hill)
This is a very popular book among CAT aspirants and really easy and simple to understand. This book also focuses on the basics first and has different levels of difficulties step by step.

3.Quantitative Aptitude for Competitive Examinations (by Abhijit Guha)
This book is quite comprehensive for various competitive exams, for both MBA aspirants and for those seeking jobs who need to prepare for the aptitude tests.
4.Quantitative Aptitude Quantum CAT by Sarvesh Verma
It is an extensive book for students aspiring to go to IIMs. It has a very simple, lucid and tailor made content revolving around CAT.

5.Quantitative Aptitude for CAT (by Nishit Sinha)
This book by Pearson focuses on in depth understanding of core topics for basic and advanced applications.


Verbal Ability Books For CAT:

1.How to Prepare for Verbal Ability and Reading Comprehension for the CAT( by Arun Sharma and Meenakshi Upadhyay)
This book is good to brush up your verbal and reading comprehension skills. It covers three important topics: reading comprehension, verbal ability and verbal reasoning. It provides sufficient practice and mock papers for self-assessment.

2.Verbal Ability and Reading Comprehension For The CAT( by Nishit Sinha)
This book by Pearson provides not only an exhaustive resource for verbal ability. It also includes numerous tests as well as integral problem solving techniques and approaches.

3.Word Power Made Easy (by Norman Lewis)
This is the go-to book to improve your vocabulary. It is not a book to be read but a book to work with daily to enrich your vocabulary.

4.High School Grammar and Composition( by Wren and Martin)
It is a very good book for people who want to improve their grammar skills. It helps to understand and conceptualise different aspects of grammar and it is a must have book for anyone with poor grasp on verbal ability or who wants to make up with the basics of english.

Read books from different genres
The ultimate key to improve your verbal ability is to read extensively and to read books from different genres. This ensures that when the time for reading comprehension comes you are well acquainted with different writing styles and topics. Reading extensively also improves your reading speeding over a period of time. There are no shortcuts here.

Data Interpretation and Logical Reasoning Books For CAT:

1.A Modern Approach to Logical Reasoning( by R.S. Agarwal)
This CAT book by R.S. Agarwal is to start with the most basic reasoning problem as it is quite simple to understand. It is segregated into different sections such as logic, statements, inferences and arguments, assumptions, conclusions, course of actions, logical puzzles, etc.

2.How to Prepare for Logical Reasoning for CAT book (by Arun Sharma)
This book by Tata McGraw Hill contains all topics to be considered under Logical Reasoning for CAT as well as other entrance exams. Each topic is explained with solved examples followed by a series of problems with varied difficulty levels to solve which gives an individual enough practice for this section.

3.How to Prepare for Data Interpretation for CAT book (by Arun Sharma)
This book focuses on all areas of Data Interpretation and Data Sufficiency. It provides and emphasizes on developing our calculations to get an edge with DI. This book also provides you with previous years questions, Model and Sample test papers.

4.Logical Reasoning and Data Interpretation for the CAT (by Nishit Sinha)
This book covers fundamental and advanced topics under the aforementioned section which are explained with the help of solved examples, case lets and exercises to do. It is useful for various other exams as well.

5.Data Interpretation (by Nishit Sinha)
Practice Book for CAT and Other MBA Entrance Examinations( by Nishit Sinha):
This book provides adequate practice and to sharpen the skills for Data Interpretation. It is also quite useful for other competitive exams like NMAT, GMAT, SNAP, XAT, CMAT, etc.

Another CAT Preparation material or book to be considered is Previous Years Solved CAT Paper:
This ensures that you are familiar with the kind of questions that are asked in CAT providing you an edge. They can be taken as mocks and the analysis of the same can provide you with great insights for your preparation.

It is always better to read newspaper for CURRENT G.K. than trying to grasp all info at once. Some of the newspaper sources which you can use to prepare this section are The Hindu, Financial Express, and The Economist.

In case, you dont like reading newspaper daily, you can go with Manorama Yearbook or Current Affairs Yearly by Arihant for General Knowledge which is published every year.

In order to prepare for STATIC G.K. section, you need to broaden your overall scope in following sections: Sports, Politics, Entertainment, Biographies, etc. So, for this, you can use Static General Knowledge by A.P. Bhardwaj and S. Chands Advanced Objective General Knowledge. These books are okay to start with if you are not someone with a newspaper reading habit from the past.

There are plenty of other books for these topics in the market, but these are by far the most popular as well as helpful books for anyone preparing for entrance exams.

Hello

If you are preparing for the JEE Main Exam you can take help from the tips given below for doing proper revisions of the the JEE Main Exam-

Do not run after the whole syllabus, revise selective and importnat topics

Do not go after new Books, read the Books and Notes you have studied till now

You can prepare from the Short Notes of JEE Main for doing revision.

Stay in touch with the Teachers and studious friends

Stay healthy and confident, do not loose hope.The preparation you have done till now is good believe on this.