JEE

Yes, you can get into Devi Ahila Vishwavidyalaya on the basis of JEE exam for its B.Tech programme. The eligibility criteria for its B.Tech programme includes JEE Main and to have passed 10+2 from a recognised board.

Clearing JEE Mains isn't mandatory for CSE at Chandigarh University. Instead, CU requires its own entrance test, CUCET, for BE CSE admissions. JEE Mains rank holders up to 50,000 are exempt, with top 25,000 ranks eligible for a full scholarship and ranks 25,001-50,000 receiving a 75% scholarship. Eligibility includes 10+2 with Physics, Mathematics, and one additional subject like Chemistry or Computer Science, with a minimum of 60% aggregate marks. 

The CUCET syllabus varies for Non-medical (English, Physics, Chemistry/Computers, Mathematics, Aptitude) and Medical streams (English, Physics, Chemistry, Biology, Aptitude).

Use Shiksha's JEE Main Rank Predictor tool. You need to enter only percentile you obtained. NTA usage the following formula uses for rank calculation from percentile.

((100-P)/100)*N+1

Where P denotes NTA score and N is number of students

Yes, there is a possibility that you can re appear for the improvement exam. But, it is to be noted that this will happen only if your board allows for it because second attempt of improvement exam is held at the same time of the general board exam. 

It is completely okay if you committed a mistake. Don't worry. JEE Main opens its correction portal soon after the application process. You can edit your details when the correction window opens. 

A total of 2,50,000 students qualify for JEE Advacnce after giving JEE Mains. These aree the top 2.5 Lakhs students who appeared for JEE Main irrespective of the total students appeared. The competition is immense.