I got 83 percentile in Jee Mains and.I am from ST category.Can I get NITs?

HELLO ANAND
Congratulations for your result and qualifying JEE mains.
since it is very difficult to predict the exact rank but we do have a backup> we have a formula to calculate the expected rank that is (100 – Total percentile) x 869010/100.
So according to formula your expected rank for present percentile for January session comes out to be 147731 . Now the expected rank might change depending on the no of candidates appearing the april session. For ex if 12 lakh candidate appear the april session then just replace 869010 by 12 lakhs. But if you score above 85 percentile then you have a very decent chance of qualifying jee mains.
But due to category you have a pretty good chance of qualifying JEE MAINS
but withe present percentile you get LOw NITS with moderate Branches.
and getting top NITS seems a little difficult
No worries since you have an april attempt left and most importantly baap of the exams i,e Advance which may directly lead you into IIts.
But if you are curious to know that which college you might land into with your percentile then you can use the college predictor link which has following features;

JEE Main 2020 College Predictor
Know your college admission chances based on your JEE Main Percentile, Home State, Caste, Gender, etc
Including premium institutes like NITs, IIITs and CFTIs, many States/ Institutes accept admissions through JEE Main. Know your chances in states like Maharashtra, West Bengal, Delhi
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JEE Main College Predictor 2020 - Predict Colleges based on your JEE Main Rank

JEE Main College Predictor – Know your College Admission Chances Based on your Rank/Percentile, Home State, Caste, Gender, Exam Result & Get ...

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ALL THE BEST FOR APRIL AND ADVANCE!!