Ashish, this is the first time that VIT had to cancel its entrance examination and conduct admissions based on Board exams and JEE Mains. And it has also been announced that weightage will be given to JEE Mains score. While the marking and weightage scheme has not been announced yet, this answer is being written with general information. Once VIT releases any official information regarding the weightage and marking scheme, we would be able to answer your question with more relevant information. Now admissions to VIT all campuses will be conducted without reservation and all seats are considered Open Merit. And VIT Vellore has approximately 100 seats allotted for Chemical Engineering and 710 seats for Mechanical Engineering. With 88% in your 12th, it might be easier for you to get a seat in any of the branches. Though the admission process might be different this year, https://vit.ac.in/viteee-counselling#:~:text=Mechanical%20Engineering%20had%20the%20second,filled%20on%20the%20first%20day. should give you a glimpse of how seats are filled according to the branch.

Ram, MHRD has requested for suggestions regarding reduced syllabus for Academic year 2020-21. And no syllabus has been finalised yet. This is going to take some time. And so it is too early to talk about Board exams already. So we need to wait to hear from the official sources because anything that we say at this point in time is just speculative.

Hi

NCERT maths book is good for class 10th board examination as most of the questions are based on the concept from NCERT but yes the number of examples given in NCERT quiet less and there are many concepts which are difficult to understand from NCERT so you can follow some reference books like Rs Agrawal or RD Sharma for better understanding of the concepts also on solving these books you will see some new pattern of questions and hots questions which are often asked in board examination.

After completing books you should solve previous year question papers of  CBSE maths board examination and mock test or sample  papers

Thankyou