UG BSC student who still in third year can apply for chemistry in this exam ?

Hello student I'm sorry to inform you but if you're in final year of Bsc you're not eligible to appear in Gate entrance examination as eligibility criteria says -
Eligibility - candidates must be in passing year or Graduate of Bachelors degree or equivalent in engineering or Architecture or Masters degree in science/computer applications.
So you need to do Msc if you're willing to appear in Gate entrance examination.

For more updates refer to the link mentioned below - https://engineering.careers360.com/articles/gate-eligibility-criteria

Feel free to comment if you have any doubt
Good luck

Hello,
The basic eligibility criteria for GATE exam is that you must first complete your undergoing course.

For B.sc degree holders, you must should have completed 4 years after 10+2 Bachelor's degree in ScienceOR Post Diploma in Science. You can also apply during your M.sc studies as the eligibility criteria is Candidates in the second or higher year of the Four-year Integrated Master's degree programme (Post-B.Sc.) in Engineering/Technology or in the third or higher year of Five-year Integrated Master's degree programme and Dual Degree programme in Engineering/Technology.
For more details about GATE eligibility criteria please visit this link https://engineering.careers360.com/articles/gate-eligibility-criteria

Hope it helps