Exam

It can lead to lower the overall grade for the course, also it can affect the student standing in the university since it shows the lack of commitment of the students, it could cause the student to miss out on important course material or concept that are covered in internal assesment.

Hope it turns out to be  helpful for you.

Generally the students are required to score more than 75% or above to enter to the top 20 percentile of their respective boards just to be eligible for joint entrance examination (JEE).

With 80 percentile in JEE Mains, you can consider the following government colleges for B.Tech:

Gurukul Kangri Haridwar

Assam University, Tezpur University, Sant Longowal Punjab with branches like civil engineering

Lovely Professional University

DIT University

Jagannath University NCR Haryana

SAGE University Bhopal

NIMS University

I.T.S Dental College, Murad Nagar

We have to convince the dean and pay 600 to attempt missed exams.

First we have to give a leave letter, if the sir accepts the reason he will retake the exams for all absented students.

Congratulations for your rank, you can easily get lower branch of NITs from north east. 

ie.

NIT Sikkim

NIT Meghalaya

NIT Mizoram

NIT Agartala etc.

It's difficult to get any government college with this percentile but here are some colleges for which you can try- 

1. Keystone School of Engineering, Pune
2. KKEI'S Trinity Academy of Engineering, Pune.

As It is mostly depandent on 12th percentage and JEE main mark (sastra will calculate like this 12th percentage * 0.75+jee main mark * 0.25)

As you have already got 98.6% in boards, hopefully you will get CSE in Sastra University.

According to me, going for the direct admission in BT.ech CSE would be a better option since you have good percentile in JEE mains. Thanks