CBSE 12th

You can opt for B.Com accounting and finance and try to score good marks in your core subject.

It is Board of Higher Secondary Education Delhi.

IIM is for Masters i.e. for the MBA program after CAT or MAT.

Yes, you can get benefit of your caste.

Yes, why not there are some institute which take entrance and they provide you admission. You can pursue marine engineering and have great future.
All the best.

Smog is basically derived from the merging of two words; smoke and fog. Smog is also used to describe the type of fog which has smoke or soot in it. Smog is a yellowish or blackish fog formed mainly by a mixture of pollutants in the atmosphere which consists of fine particles and ground level ozone. Smog which occurs mainly because of air pollution, can also be defined as a mixture of various gases with dust and water vapor. Smog also refers to hazy air that makes breathing difficult.

B.Com would be a better option and you can do MBA from a top B-School and business maths is not mandatory for B.Com but you will not be able to do B.Com (Honors).