Hi Shubham,

General criteria for BBA course is that a candidate should have passed 10+2 examination from recognised board, university or council with a minimum 50% marks or 45% marks respectively depending upon program / institute they are aspiring to take admissions. Almost all colleges accept NIOS student except Amity University,  As you got 70% in class 12th so you will definitely get admission to BBA course.

All the best!!

Yes...you can apply for iims if they providing BBA course.

Hello shubham,
Yes ofcourse you can apply for a bba cource through NIOS here is the listed college you may apply
Below given BBA college accept NIOS certificate:-

>> Loyola Institute of Business Administration (LIBA), Chennai
E-mail :info@liba.edu
Website :http://liba.edu/

>> Department of Management Studies IIT Madras, Chennai
E-mail :doms@iitm.ac.in
Website :http://www.doms.iitm.ac.in/domsnew/

>> Great Lakes Institute of Management, Chennai
E-mail :query@greatlakes.edu.in
Website :http://www.greatlakes.edu.in/

>> Institute of Financial Management and Research (IFMR), Chennai
E-mail :ganapathy.s@ifmr.ac.in
Website :http://ifmr.ac.in/

>> ITM Chennai, Chennai
E-mail :chennai@itm.edu
Website :http://www.itm.edu/chennai/index.php

>> Chennai Business School (CBS), Chennai
E-mail :mail@cbs.org.in
Website :http://www.cbs.org.in/

>> Academy of Maritime Education and Training, Chennai
E-mail :amet@vsnl.com
Website :http://www.ametindia.com
Thank you for asking
Best of luck for your future