JEE

If you cleared IIT-Mains, then you are eligible to get admission in any decent engineering college. A score around 190-220 is a good score to get into NITs. You can try to score good in IIT-JEE Mains, so that you can fight for IITs.

There is no provision of top 20 percentile students to join IITs without appearing for JEE Mains.

No, you need to score above 200 marks to get admission.
All the best.

If you get above 180 marks and you belong to the same state, then you have more chances.
All the best.

You have to take an entrance exam and qualify the same if you want to pursue engineering.

Check out the link below for details:
https://www.shiksha.com/top-engineering-colleges-in-bangalore-accepting-jee-mains-score-rankingpage-44-0-0-278-6244

If you have completed class 12th from state board or CBSE board with science stream then your can prepare for JEE Mains or CET exam.

FIIT JEE, Chandigarh
Aakash Institute, Chandigarh
Vidyamandir Classes, Chandigarh
Allen Career Institute, Chandigarh
GIIT JEE, Chandigarh
Ace Tutorials, Chandigarh
Phi Tutorials, Chandigarh
Regional Faculty of Science, Chandigarh
Firoz Khans Competition Zone, Chandigarh
Induction Physics Academy, Chandigarh
These are the top coaching for IIT JEE in Chandigarh.

You should re-appear for class 12th board exams as it will become invaluable if you score good marks in JEE mains because your class 12th score is very low.

It would be around 50, 000 as board marks won't play any role from this year onwards in JEE Mains exam.