Class 11

It is of no problem if done before registration which is commonly done by mid-term in 11th.
It is easy to switch from science to commerce or humanities, commerce to humanities but not from humanities to commerce or science or commerce to science (It doesn't mean that it's not possible).
But these arguments were valid till last year. Earlier this year, there were some news about the same.

Hi Anmol,
You should take science stream and in another subject, either you can take IT subject because you have scored good marks in computer science. After that, you can pursue engineering in computer science and your basic will be clear and you will have more knowledge.

You are advised to appear for NDA exam after 10+2 board conducted by UPSC to join Defence Services as an Officer. You can also join AFMC, Pune to become a doctor in Defence Services.

Hi,
It is better to take PCM and computer science in class 12th. In undergraduate level, you can go with honors in any of the subjects from the combination as per your choice. You can also think of B.Stat honors from Indian Statistical Institute by cracking entrance exam after completion of class 12th.

You need a CGPA of 4 and higher to apply to ivy leagues. Your overall profile that includes co-curricular, sports, community services, etc. should also be impressive.

Hi Ayush,
SAT can be given anytime after 10th as the scores are valid for 5 years and the best of the scores are taken by the universities automatically from college board if you have taken it more than once. It happens 6 times in a year. You may check all the details of registration and test dates.
www.collegeboard.org

Hi,
Here are the colleges for you:
St. Joseph Public School
Alluri Sitaram Raju Residential School
St. Ann's Public School
Nav Jeevan Public School

Chennai has the best B-schools.