i am in final year, going to apply for GPAT exam, but since I have one backlog in 5th semester of 3rd year, I don't have CGPA/SGPA on marksheet. so what should I fill in the column of 3rd year CGPA in application?

If you have a backlog in 5th semester and your 3rd year CGPA/SGPA is not mentioned on the marksheet, you should fill 'NA' or 'Result Awaited' in the 3rd year CGPA column, as applicable. GPAT eligibility is usually verified at the time of admission, not during application. Ensure you clear the backlog and meet eligibility criteria before counselling.