Hello Shruti,

Going by the last year trends and considering you are general, MSc chemistry closed in 51k in the round 7 of JoSAA. So there is very less chance if you will be getting MSc with chemistry, however, you can definitely get MSc in mathematics till round 5 or more. If you still want that particular course, you can go for CSAB Special Round where you can definitely get a seat in MSc chemistry. I am giving you estimates considering you don't belong to any particular reserved category. I hope it helps.

I am attaching last year cutoffs for NIT Patna https://engineering.careers360.com/articles/jee-main-cutoff-for-nit-patna 

Thanks