Hello Aspirant,

In order to take admission in NITs for Undergraduate Engineering programme, You need to appear JEE Main Entrance Exam which is a Natioal level Exam and to get admission in BITs colleges you need to appear BITSAT Entrance Exam conducted by University. You can check the complete eligibility to apply for the exam with the given below links.

https://engineering.careers360.com/articles/jee-main-eligibility-criteria

https://engineering.careers360.com/articles/bitsat-eligibility-criteria

In case you have any other query then let me know.

Good Luck!