B.Sc

By completing a Bachelor's degree course, you would be eligible to attain a Bachelor's degree through the concerned university. You need to prepare well for the exam, you can also use the past years sample papers.

Please refer to the link mentioned below:
https://goo.gl/tpWWPF

Yes, you can as you need to submit the top 5 subject's percentage.

Hi Vaishnavi,
Applicants must have a minimum of 75% (65% for SC/ST/PWD) marks in aggregate in maths and science subjects (Physics/Chemistry/Biology) in class 10th board exams and a minimum of 60% (50% for SC/ST/PWD) marks in aggregate in maths and science subjects (Physics/Chemistry/Biology) in the class 12th board exams . For details and updates please visit the KVPY website.
http://kvpy.iisc.ernet.in/main/eligibility.htm

You should opt for BCA for fast career growth.

Hi Tanu,
You have to check the cut-offs of the various colleges under DU. As of now, it has not been announced. Please keep checking Delhi University's official website for the cut-off and merit list. For previous year's cut-offs, please refer to this article:
https://www.shiksha.com/humanities-social-sciences/articles/du-cut-off-trends-for-past-years-blogId-12697