sir i given my class 12th exam in 2018 and reappeared for improvement exam in 2019 in all subjects so during filling the form of jee mains for 2020 which marks i have to fill. whether improvement exam or class 12th marks.
As per your requirement, i would say that you have to mention passed in application form though it will show your low percentage. If it gets improved then you can show it at the time of counselling but not now. Your improvement results are not came yet though you can't mention appearing.
If your improvement marks are already out, then you have to put your improvement marks only in the form.
Confirm from the jee main site to know the exact details.
IIT/JEE 2020 Online Preparation
Crack JEE 2020 with JEE Knockout Program, If you Do Not Qualify- Get 100% MONEY BACK