CBSE 12th

Of course, Bachelor of Arts is an undergraduate course that students of any stream can go for. Understandably, it might be a challenge for the first year, as you will not have learned the basic concepts, but no worries. Psychology is a subject that, if you are interested in the subject genuinely, you can surely catch up. Plus, reading your friends' class 11th and class 12th books might help (if you have the time for that, that is). Best college/university would depend on where you stay, where you are prepared to move, and, of course, your class 10th, class 11th and class 12th standard scores. It is the best, if you research online depending upon your choice of location and subject choices etc. Earning in lacs, well, not immediately, of course. The most lucrative (since you ask about being able to earn in lacs) field in psychology would be Psychiatry, but since you haven't taken Biology, and I assume you don't want to go into Medicine, I won't dwell on that. Other lucrative psychology fields are clinical psychology, sports psychology, forensic psychology, student counselling, industrial-organizational psychology, and neuropsychology. All these are quite lucrative as you climb up the ladder which will happen with time, patience and hard-work. It also depends upon where you are employed, whether you have a private practice or if you are affiliated to a hospital. On an average, psychologists who work in private institutions are paid higher than those who work in government-run institutions. For knowledge sake, the least lucrative fields of psychology are social work, rehabilitation counselling, and child care work.

Yes, there is a requirement to qualify mainscope:
After your graduation from a B.Sc. Mathematics degree, you can pursue courses like MCA M.Sc. IT, actuarial sciences, MBA or M.Sc. In Mathematics. To get the most out of this course, it is best to immediately pursue higher studies after having completed your graduation. The world is your oyster afterwards, with a plethora of opportunities in research, academia, and technical institutes. Career opportunities can include jobs at financial companies, software developers, marketers and bankers; everyone wants a good mathematician. In applied mathematics, you'll have to creatively solve problems in business and social domains. Data analytics, a field which is the talk of town, often needs people who are good with numbers and understand data. With excellent mathematical abilities, you might just be picked up by political or military intelligence bodies to work as a crypto analyst, who deciphers encrypted messages.