Science

Yes, you can do, but it will not be beneficial for you. If you want to pursue masters, then you can go for M.Tech that will give you better career and scope in your field.

It depends, where your interest lies, both are different career options I would suggest you to look for the job opportunity and brief knowledge of the concerned.

Hi,
Yes, you are eligible for the B.Com.
But, as you are science student, you need to work hard initially, because things will be new for you. The laws, concepts, and the formulas etc .You need to focus more on accounts, as the things are totally new for you. Don't worry, you just need to some hard work and everything will be fine for you.