Science

If you are interested for this course, you can apply online with the required information and the admission is based on marks obtained in the qualifying exam. Refer to this link –
http://www.shcollege.ac.in/ApplicationForms

It depends on your class 12th subjects. If you are from science background then you can go for it.

Masters in Hospital Administration will be better as far as scope is concerned. You get plenty of fields to try in after doing your Masters in Hospital Administration. The course has scope in both India as well as abroad.

Go through the link below for details:
https://www.shiksha.com/science/colleges/forensic-science-colleges-Tamil-Nadu

Yes, you can. As per the eligibility criteria, you should clear your 10+2 or equivalent examination in Science stream with at least 50% marks in mathematics subject. Admissions are based on the entrance exam and merit. To check the colleges in India that offer B.Sc mathematics, please see here-
https://www.shiksha.com/science/colleges/b-sc-mathematics-colleges-india

Checkout all the details related to ICAR AIEEA from the link below:
https://www.shiksha.com/science/icar-aieea-exam

In my opinion, Masters in hospital management has better scope than M.Sc in environmental science. After completing this course, you can work in the following profile with better salary packages-
Hospital HR
Medical administration
Hospital Operations
Quality
Hospital marketing and sales

The scope after forensic Science, in Tamil Nadu is comparatively less than other states. To see the type of jobs you can be offered, please check this link-
https://www.naukri.com/forensic-jobs-in-south-tamilnadu

B.Sc has better scope than B.Com. This programme has become one of the highly studied degree courses in Indian institutions. You can pursue M.Sc after B.Sc and further get into research areas and can even look for any other job oriented professional course.

There are plenty of fields you can choose with B.Sc like agriculture, animation, aquaculture, aviation, biochemistry, bioinformatics, computer science, dietetics, etc. If I talk about the scope, agriculture, computer science and dietetics can be better comparatively.