Hello,

To get into NIT your rank must be below 2-3k. That might be your general rank or categorical rank. As you belong to SC category a mark near to 250 will do. You will be eligible for NIT. If you want to get a branch like CSE or ECE then you have to score near to 270 or more. As rank considered as really low and are below 1K. Getting 1k rank is not easy.

There are lots of preparation to do and many questions to solve then only you will be enough confident to answer a question which will me confusing. Paper has negative marking that says that you can't make guess work. If you do you will lose mark applied  answer you gave  is wrong.

So look into all the facts and prepare such that with all your hard work you can score upto 250 marks.

Hope it helps!