Well smriti.

You should choose between maths and chemistry according to your interest and strength's.If you are not a good in maths you can definitely choose chemistry because there are many theory questions and less number of problems,so you can score easily.so when compared to maths and chemistry, Chemistry would be better to choose

hello smriti

you can check out the complete set of books for jee mains chemistry and mathematics at https://engineering.careers360.com/articles/best-books-for-jee-main-2019 . you need not buy all of them but you can consider 1 book for theory and 1 for problems.