Yes caste certificate is must if you are applying under SC  STor OBC category to avail reservation quoat benefits else you shall be considered under General category . 

List of requirements shared below for NIT Bhopal. 

https://www.google.co.in/url?sa=t&source=web&rct=j&url=http://www.manit.ac.in/sites/default/files/addmissionsection/new%2520pdf%2520m.tech_.pdf&ved=2ahUKEwiDqovZt-zdAhWHfSsKHSZxB9wQFjAAegQIAxAB&usg=AOvVaw2j98pOnE7EB7ABIGfqhFQC