Hi Vishal,

See this is very much harder to study only NCERT and  previous year question papers and get 90/100 in Chemistry in JEE Mains Exam. I am not saying it is impossible, if you study and memorize each and every page of NCERT and understand every concept well and practice out last 10 years question papers, then it might be possible.

Else you will have to go through a good book other than NCERT for your JEE Mains preparation.

Refer here to see Best books for JEE Main 2020 - https://engineering.careers360.com/articles/best-books-for-jee-main

Feel free to ask doubts in the Comment Section.

I hope this information helps you.

Good Luck!