Engineering

Minimum marks you must score to get a chance for a seat in IITs you need to score around 150+. Competition is fierce for top IITs. A score around 45 was cut off for JEE Advanced. This year 34425 qualified in JEE Advanced. Minimum marks -73 and Maximum marks-29. Comparison-
JEE Main 2018 cut offs for

Many options are available. Check COMEDK, university level entrance exams, ICAR for agriculture.

It will be bit difficult to get admission in Dhirubhai Ambani Institute of Information and Communication Technology-DAIICT. For B.Tech (ICT) - Min Rank is around 4000, and Max Rank around 15000, For Gujarat quota minimum rank is around 3000 and max. Rank around 54000. For B.Tech (Hons) CS Minimum Ra

It's not necessary actually. It's bifocal subject. You have other options as well like Electronics, Scooter Science, etc. But, most preferred option in CS as you can score more marks easily in it.

There are many aspects to aeronautical/astronautical engineering including:
Propulsion
Avionics/control and communications
Material Science
Thermodynamics
Fluid mechanics
Dynamics
Mechanical engineering
And I'm sure there are interesting things in the biological effects on humans, etc., sometimes called Hum

YOU can get the list of good collleges through the given link:
https://www.shiksha.com/science/bsc-chp8.

Please use Shiksha College Predictor:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor.