Here I am giving you information about main subjects for Graduate Aptitude Test in Engineering below :

General Aptitude (GA) component common in all papers
Aerospace Engineering
Agricultural Engineering
Architecture and Planning
Biotechnology
Chemical Engineering
Chemistry
Civil Engineering
Computer Science and Information Technology
Electrical Engineering
Electronics and Communication Engineering
Geology and Geophysics
Instrumentation Engineering
Mathematics
Mechanical Engineering
Mining Engineering
Metallurgical Engineering
Physics
Production and Industrial Engineering
Textile Engineering and Fibre Science
Engineering Sciences
Life Sciences

GATE Exam Pattern:
Duration is of 3 hours.
Online Computer Based Test
A single paper with 65 total questions
Maximum marks are 100
Questions will be multiple choice as well as numerical type
10 questions will be on General Aptitude carrying 15 marks.