Science

Hi Shri,
You may pursue your B.Sc (Hons) in Physics, Chemistry and Mathematics. You may explore engineering areas such as Materials engineering, Process engineering and Corrosion engineering.

Dear, it is not possible for you to get admission anywhere if you have not cleared all the subjects in 12th standard.
I would suggest you to challenge the evaluation of your failed subject, If you are confident enough you should do as suggested .
Just go to any of the board office of the respective board and file your grievance .
I hope you pass the subject after challenge evaluation, and then you would be able to take admissions .

IIM's I would say aren't the end of the world and you can very well reach similar or greater heights in your career despite the IIM tag. You can look at other Indian MBA B - Schools or Foreign B-Schools, that don't give as much weightage to 10th and 12th percentage like ISB.
Also, I would say it is important that you introspect a bit about your career and look for ways to progress where your past profile would not be a hurdle.