Hi aspirant.. Educational requirements are more or less same for regular Universities and Open University. 

If you want to pursue your B.Sc in distance mode IGNOU is the best option for you.

Eligibility- 10+2 or intermediate or equivalent  from recognized Board. There is no age limit to pursue this course in IGNOU.you can get more details on official page of IGNOU University.Minimum duration to complete this  course is 3years and the maximum limit is 6years.

You can also apply in enlisted College given ahead-

Dr.B.R Ambedkar Open University - Hyderabad

School Of Distance Education, Bharathiar University, Coimbatore.

Netaji Subas Open University- kolkata

Annamalia University- Tamil Nadu

Punjab Technical University

Nalanda Open University- Bihar

Hope you got your answer.

Good Luck