Psychology is very interesting subject. You can pursue this course after 12th class in any subject like science, arts or commerce infact. Psychology is the science of human behaviour, mind feeling, thoughts, unconscious phenomena etc study.
BSC in psychology means you are science student and take this course. Here you have to study lot's of subjects like general psychology, social psychology, physiological psychology, human development, social behaviour, experimental psychology, biological basic behaviour etc.
For admission in BSC in psychology you have to pass in science group 12th class with minimum 50% marks. In Chennai you can get admission in psychology through merit list as well which is basis of your 12th marks. Some colleges organised entrance examination so you have to check. But for good college every year you have to get good marks in 12th like 80% or above 80% then you will get easily chance in admission chennai psychological college.
All the best.