Hey Saikumar, 

Yes a person who have backlog in their Bachelor's degree can write GATE(Graduate Aptitude Test in Engineering) Exam but make sure that clear them before getting admission into any college.

Some basic eligibility criterias for giving this exam :

• There is no age limit prescribed for giving this exam  
• You must have passed you Bachelor's degree in any of the course B.Tech/BE/B.Pharma, B.Arch, B.Sc (Research)/BS from a recognized university or institution. 
• The candidates who are in final year of their Bachelor's degree can also apply.
• There is no minimum percentage specified for giving GATE exam.

Good Luck!