According to the rules you need to have to pass 10+2 to answer JEE Mains/Adv. Now to enter 12th, you would obviously need to pass 11th standard. Hence, Yes it is very important and one of the most basic requirement.

Yes,

For sure you have to pass 11th class and 12th class for the JEE entrance Exam.

This is the basic criteria for JEE mains and advance you can also get more of the criteria from the official website .

Ofcourse it is necessary to pass 11th std , you need to get a good cutoff score in over all inter to apply or attempt any engineering enterance exams the marks required is above 60%.

Dear aspirant

It is important to pass 10+2 in order to get through the JEE criteria.

Duly note that 11th standard is not equally important. But, you need to have a passing certificate for grade 12th in order to apply for the same. Feel free to ask more on the same if required.

Thanks.