It depends on the College/Institution that you want to take admission in. If you belong to General Category Institutions expect you to have a minimum aggregate of 50-60%. And if you belong to Reserved Categories, your aggregate should be between 40-50%. Now all Institutions do not conduct admissions based on Entrance Examination. There are few Institutions that conduct admissions based on merit scored in 12th. For those Institutions, you need to have greater percentage in your 12th, may be like 80-90%. But for Institutions which conduct admissions based on Entrance exam, the required aggregate might be 40-60% depending on your Category.