Hello Vinay!!

NCERT books are a standard reference book for students under the CBSE. Major portions of questions in the CBSE board exams generally derive from NCERT textbooks. The central board makes its examination questions based on NCERT textbooks.

Curriculum Alignment: NCERT Syllabus provides the basis upon which CBSE designs its curriculum and exam papers. This way, all the material contained in textbooks is put under test and hence, students are eligible to secure the marks if the students have read NCERT books properly.

Question types: Questions in the board exams are normally taken straight from the NCERT textbooks or framed with a basis on the concepts and topics from these books. The question types may include multiple-choice questions, short answer questions, and long answer questions.

Preparation Strategy: Students should have an in-depth study and practice of what they study from NCERT books. Revisions must be done regularly and previous years' question papers need to be solved so that students get accustomed to question patterns and the type of content emphasized in them.

Additional Resources: Though NCERT books are inevitable, it is always advisable to refer to extra supplementary material or practice papers to get a bit more understanding of the concept and ensure complete preparation.

In short, while not all the questions in the board exam in CBSE are a direct lift from NCERT books, a large percentage of the questions follow content studied from these books. Hence proper preparation with NCERT books would be one of the key strategies to success in exams conducted by CBSE.