Pls give me all detail about IIT exams,when apply,how many times apply,

Hello Abhishek

For admission to Undergraduate Engineering courses (B.Tech)  in IITs, candidates have to qualify the JEE Advanced entrance exam.
Admissions to the Bachelor’s, Integrated Master’s and Dual Degree programs in 23 IITs is on the basis of JEE Advanced ranks.

Now, JEE Advanced can be attempted by candidates only after qualifying JEE Mains exam. Firstly, I will tell you the detailed information about the JEE Main exam.

Joint Entrance Exam (JEE) Main is the national level engineering entrance exam. It is a undergraduate entrance exam for admission to B.E/B.Tech programmes. JEE Main 2019 exam is conducted by National Testing Agency (NTA) and NTA is conducting the exam twice a year in January and April.

Through JEE Mains exam -
- Candidates can get admission into NITs, IIITs and CFTIs.
- Can qualify for JEE Advanced exam. JEE Mains is the qualifying test for JEE Advanced.

To appear for the JEE Main exam, candidates will have to fulfill the eligibility criteria. Eligibility criteria is as follows-

1. Candidates are required to have studied five subjects in Class 12th or equivalent examination. The five subjects are-

Physics
Mathematics
Any one language
Any one of (Chemistry, Biology, Biotechnology, Technical Vocational Subject)
Any other subjects

2. Candidates are required to have scored 75 percent minimum marks in Class 12th examination or be in the top 20 percentile in class 12th exam conducted by the respective Board.
There is relaxation in age limit for candidates belonging to the reserved category. SC/ST category candidates are required to have scored 65 percent marks in Class 12th examination or equivalent.

3. There is no age limit to appear for the JEE Main exam.

4. Three attempts are given to the candidate for the JEE Main exam. Candidates can appear in the exam for the three consecutive years. As I have mentioned that from this year onwards, exam is being conducted two times a year, candidates can appear in both the exams in a year and it will be counted as one attempt only.

Check the detailed eligiiblity criteria using the link below-

https://engineering.careers360.com/articles/jee-main-eligibility-criteria

JEE Main Syllabus and exam pattern

JEE Main exam is held in Computer Based mode. Duration of the JEE Main exam is three hours. Multiple Choice questions are asked in the exam from three subjects. Subjects are Physics, Chemistry and Mathematics.
30 questions are asked from each section. There are tottal 90 questions in the exam.
For every correct answer,four marks are awarded and for every incorrect answer one mark is deducted. The exam is of total 360 marks.
It consists of topics from Class 11 and Class 12. Candidates should study well in both the classes.
NCERT textbooks are the best for clearing the concepts. But to gain in depth knowledge, one must study and practice questions from other books as well.

JEE Main Important Dates-
JEE Main 2019 exam will be conducted twice a year in January and April. JEE Main (January exams) application forms were available from 1 September 2018. Last Date for the submission of online forms was 30 September 2018.
JEE Main exam dates- 9 January to 12 January.

Candidates qualifying the JEE Main exam are eligible to appear for the JEE Advanced exam.
JEE Advanced exam is also held in Computer Based mode. The exam is held once a year. JEE Advanced exam can be attempted two times in two consective years by the candidate.
Application forms for the JEE Main April 2-19 exam will begin from 8 february 2019 and application process will end on 7 March 2019.
Exam Dates- 6 April to 20 April 2019.

Exam pattern of JEE Advanced is as follows-
JEE Advanced will have two compulsory papers- Paper 1 and paper 2 of three hours duration each.
Questions will be asked from Physics, Chemistry and Mathematics. Multiple Choice questions and numerical questions are asked in the advanced exam.
Some questions in the exam may have multiple correct options so according to the particular question full, partial, zero or negative marks are allotted to the candidate.
Check th e detailed exam pattern for more clarification-

https://engineering.careers360.com/articles/jee-advanced-exam-pattern

JEE Advanced Syllabus
Syllabus of the exam is of advanced level then the JEE Main exam. Candidate shave to work hard to qualify the exam and clear the cutoffs of IITs for admission to their preferred engineering branch.

JEE Advanced Important Dates
Application forms will release tentatively from 2 May 2019 and exam will be conduted on 19 May 2019.

Do let us know if you have any other doubt.
Good Luck!