hi,

to appear in jee main exam, you must have studied physics , chemistry  and mathematics is 12th course, there is no certain qualifying mrks to appear in neet exam, but if you want to get admission in iits, nits or cftis you must score  75% (for genral category and obc category) aggregate marks in 12th exam, for sc/st candidates marks criteria is 65% aggregate marks in 12th exam.

a candidate apply for three times in jee main exam, if you have passed 12th is 2020, you may appear in jee main exam in 2020, 2021, 2022.

hope it would help.

hey

YES they can fill  jee main application form and appear for the exam. But there no use of it as no institution will give them admission, because basic requirement for admission in btech is PCM .

for more information about jee mains refer this article

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