Interview was only judgement criteria.
(apart from that OGPA >7.0 upto 8th semester).

My interview went around for 25 min& around 10 questions were asked.
They are as follows:
1)My iitjee rank & why i chose env engg
2)Area of interest
3)questions on past training and internship
4)Global warming scenario,questions like which countries are mainly responsible for global warming,India's contribution in it,major greenhouse gases etc.
5)why i want to join ongc
6) Environmental impact assesment procedure ;major changes in EIA
7)one case study

1)prepare yourself for frequently aksed qns like
-why u want to join company
-how will you be an asset to company
-what will be your job
- your strengths and weakness
-past internship and training projects
-current affairs
2)be confident and honest during interview
3)Have good communication skills
4) wear proper formals on interview.

Selection was totally based on performance in Interview.
Out of 14(in our branch) ,4 got selected.
GPA wise i was 2nd last of all. .
For my interview i prepared myself for few qns like
-why i chose env engg
-area of interest
-internship and training work etc
I tried to focus my panel on my strengths and remained honest throughout interview.
Finally sucess was combo of pre-planning ,confidence and luck.