Which is the best book for class 9 CBSE

For scoring very high percentage in board examination, I suggest to go through NCERT books only.If you are planning to crack I.I.T. entrance examination or medical entrance examination then study additional books. For mathematics, I recommend books by RD Sharma and RS Agarwal. RD Sharma is recommended for topper students. RD Sharma has added few questions of very high level. Whereas mathematics books by RS Agarwal is of medium level. Lots of model papers and revision tests are there at the end of each chapter.

For science subject i.e. Physics, Chemistry and Biology, books written by S Chand are best suggested.Books written by RD Sharma, RS Agarwal and S Chand are recommended in addition to NCERT book. NCERT books are core books. You have to be thorough with NCERT books to score high percentage in board examination. For your kind information grading system has been abolished from 10th class. Again board examination system has been introduced from 2017 onward.

For scoring good in exam, a student needs to read other books also which are a little different than text books issued by board or school.
These books used for further reference and detailed study of concepts few such books preferred by most of the students are listed as follows:
-books by S.CHAND publications written by Lakhmir singh Manjeet Singh for subjects like biology, chemistry and physics these books consists of detail explanations of all the concepts with activities.
-Books by Dinesh Publication for all the subjects
-Books by Pradeep Publication
-For maths R.D Sharma is the most preferred book, this book also helps in building up concepts.
-For sample papers use evergreen 100% success which gives many sample papers and model papers with solutions

As a teacher who has taught students of CBSE for more than 15 years, I am firmly of the opinion that student need not study any other book except NCERT books in all subjects for the purpose of Board examination. This equally applies for a student of IXth standard also. NCERT books along with sample question papers from U-like Publisher or Evergreen Publication is sufficient for a student for getting more than 90% marks in CBSE examination. R.D. Sharma Mathematics or books of Pradeep Publication help students for higher level examination like NTSE.
However, for practising English unseen portion, the book of BBC (Brajindra Book Company) is necessary.