Dual

Hi Ramesh Pal,
Kindly mention your preferred location:
https://www.shiksha.com/bba/articles/integrated-mba-programmes-in-india-blogId-15044
https://www.shiksha.com/business-management-studies/articles/your-career-after-doing-an-integrated-bba-mba-blogId-4539

Yes, of course you'll be eligible to do that. You just need a Bachelor's degree for UPSC. Be it a 4 year programme or 5 years.

As you have just prepared for it, so don't worry, everything is going to be fine.
Good luck.

Well, you should definitely opt for Thapar. Thapar University is one of the best you get.
They have scholarships too making it great for students from abroad to get a quality education and hone their skills. It has been rated amongst the top-ranked innovation-driven private institutions and technical institutes in the country, Thapar Institute of Engineering & Technology has been accredited with an 'A' grade by the National Assessment and Accreditation Council (NAAC).

There is nothing like required score. As it is rank based, on your merit in comparison to other applicants. Higher you score, better the chance. Though, there exist some reservations too.

Hi Keerthi Rajan,
Kindly mention the paper/exam name which you wish to know about for better understanding.

I guess, you are a bit confused in understanding the eligibility criteria with 10+2. It means, your class 12th or PUC grade, not your class 10th. So, better start focusing on your subject to get your dream college.

There is no such best specialization. All the specializations go well with the dual degrees.

All the IIT's
IISER's
NISER, Bhubaneswar
BITS, Pilani
IISc, Bangalore.

According to me, chemistry has more scope:
You can become a scientist in a reputed lab if you know chemistry, wherein, by doing maths, you can still become a researcher but not as good as a scientist.
You can do research in the medical field, chemical field, human body, forensic science and many other. You can make your career in the teaching line as well. Now, the choice is all yours.