IIT

For admission in IIT colleges you must qualify Jee B. Arch as well as Jee B. Tech. Your Hsc result should also be more than 70-75%.That's all for getting admission in IIT's.

To become astronaut you will have to become a Pilot or Flight Engineer. Opportunities to become Astronaut are very few ( you can count them on fingers). In India astronauts were inducted from Fighter branch of Indian Air Force. I will recommend that complete Aeronautical Engineering degree and learn to fly. You can then apply to organisations such as NASA to fulfill your dream.

Hi Satyam,
The cut-off vary's year after year, hence, I would request you to attempt your paper to the best of your capability. List of colleges offering Chemical Engineering on basis of GATE score:
http://goo.gl/43U0UX
Kindly filter out the branch / college / location as desired from the above link.
I hope this information helps. Please feel free to revert.
Wish you luck.

There is no separate examination conducted by IIT madras, enrolment in IIT madras is done through JEE advance and its one of the toughest engineering examination across India

allen or resonance or vibrant all threes are good

Don't panic! If I assume you are in +1,then you have ample time. don't worry. Start from the basics of the subject and make yourself strong. Follow HC Verma or DC Pandey and make sure you solve maximum of the problems atleast from HCVerma. As I said you must make your basics strong coz when you go to +2 there is a more chance of forgetting the concepts. So "FOLLOW THOSE BOOKS - SOLVE PROBLEMS - REVISE BEFORE +2 DURING HOLIDAYS ONCE ". Moreover make yourself more stronger in Maths & Chemistry.

yes the course is same.

IIT offers dual degree after 12th that is B.Tech plus M.tech and the total duration is 5 years , you need to have minimum 75% in class 12th or you should lie in top 20 percentile of your respective board in 12th to get into IIT