Colleges in Tamil Nadu

Admission to the above-mentioned course is based on your 12th class percentage. I would suggest you to get in touch with the college officials to know if they would consider Diploma also.
Link for contact details: http://www.remocollege.com/contact.html

Ph.D. in environmental Science is not offered in Anna University, Chennai. Refer the link to know the specializations offered under Ph.D. https://www.shiksha.com/university/anna-university-chennai-3084/courses/phd-bc.

In government engineering college, I think, it is 70k per year.

Chemical Engineering and CSE are both no way related to each other. If you have a desire interest in learning computation, Coding, if you love maths. Then, CSE can be a better option. Also Job prospects in CSE from IIT is much better. Though Chemical has its own advantages. Its totally your decision

Your chances for call is average. 50-50 chances are there for call. So, best of luck dear.

Even if you haven't taken Maths in your 12th, you can apply for BBA. The selection procedure is based on 12th percentage, if you have a good score you can get a seat easily.

Yes, you can apply for it. There are high chances of you getting a seat if you apply.