Ash, BSc Psychology is a 3 year undergraduate course which can be pursued by anyone who has completed their 12th board exams. The eligibility criteria states that you should have done your 10+2 or equivalent examination from any reputed board. So yes, irrespective of what stream you have taken, you are eligible for the course.

Most institutes ask for at least 55% marks in your 12th board examination and the selection process involves a merit- based entrance examination which varies from college to college.