Hey varsha,

Basically the admission in IIT's and NIT's does not include the 10th and 12th exam marks. A minimum of 75% is enough for the eligibility criteria. But in order to get admission in IIT and NIT you need to crack the JEE mains and advance exam and you need the crack the cut off for your category. Then you will be albe to get the desired course and college. Prepare for JEE exam. It will take you into greater heights.Check out the below given link to know more about JEE.

https://engineering.careers360.com/articles/jee-main-cutoff

Hope this helps

All the best for your exam.!!