Sir, iam studing 10th class i want to apply for iiit when should i want to apply after 10th or in 10th class?

Hello Suvarna,

First of all complete your senior secondary education i.e. class 12th.
Physics, Chemistry and Maths are compulsory subjects if you want to join an IIT(or to be an engineer from any college)  for the 4th subject you will get options which include computer science, Economics, physical education and some other depending on your school and board. If you are from CBSE board then your 5th subject have be English(I have no idea about other boards but I think they follow the same pattern) .

Join a coaching center if you can. It's not compulsory to join a coaching center, you can crack the Joint Entrance Exam on your own too but they give you a proper direction and will tell you about tricks and short cuts that will come handy while you write JEE. Choose your coaching schedule according to your scool timings and don't ever neglect your studies at school because of their 40%tile policy where your 12th class percentage will also be taken into account while calculating your JEE rank ( I have seen people scoring very good at JEE still not getting into an IIT because of their low percentage in boards and the reverse is also true.)

Make a time table for yourself.
Fix your study hours for some morning time is best while others prefer late night studies.
Keep your basics clear and don't just focus on tricks( they are important in JEE but they won't help you in boards).
Keep giving mocks and keep a track of your progress. Make sure you work on your weak points and at the same time make your strong areas your strength.

All the best!!