Dear Rajasree, you necessarily needn't have Psychology as a subject in your 10+2. If you have completed 10+2 with a minimum aggregate of 50%, you are eligible to pursue B.Sc Psychology. Few Institutions prefer students from Science stream while few Institutions have no subject preferences. Few Institutions conduct admissions based on the merit scored in your 10+2 while few Institutions conduct Entrance Examinations. Eitherways, you neednt have Psychology as a subject in your 10+2.