Hello aspirant

College closing and opening rank for courses vary each year according to percentile and other factors. as you have mentioned you are from st category and you are getting 84 percentile then your expected AIR rank will be around 169700 .

As you have not mentioned you home state it is difficult to assist you with proper details as nit 's have home state quota . i am considering you from Delhi then best college you can get with 84 percentile are

1. Nsit
2. DTU
3. Igdtuw ( girls)
4. IIIT DELHI

You can get college list according to your percentile using careers360 predictor tool

https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Hope this will help

Thank you