IIT

Refer the following:
https://www.shiksha.com/science/articles/kvpy-exam-2021-advantages-of-the-scholarship-programme-blogId-46239
Thanks.

It depends on people to people, but according to me B.Tech is far good than BCA as you will get more opportunities than in BCA.

Please check the last year's cutoff so that you can get best idea for your admission.

IITs are surely the dream of millions. But it is a general misconception that IITs are for only B.Tech and M.Tech courses. A candidate who has completed his/her B.Sc can also get admission in the IITs for the masters. For this, they have to qualify the IIT JAM exam.
The IIT JAM is conducted each year for those who want to get admission in the IITs after their B.Sc in the courses like physics, maths, chemistry, biological sciences etc.

Pandit Deendayal Energy University is considered the best college for a B.Tech in Chemical Engineering course in Gujarat. The professors here possess immense expertise in their subjects and they try to offer the best learning experience to you. For more information, visit- https://www.shiksha.com/university/pandit-deendayal-energy-university-pdeu-gandhinagar-54332.

The simple answer is that you should study night and day.

90% in 12th is a very good score and 100 marks is bit good score too, you may get into NITS, check your chances of getting into NITS by Shiksha college predictor.

Your rank should not exceed 1500.

You need to score a rank under 1500.

You need to give JEE advance.