Hello,

To be eligible to apply for AFCAT Ground Duty Technical you must have passed 10+2 with Mathematics and Physics with minimum 50% aggregate marks and must have passed a minimum of four year graduation / integrated post-graduation qualification in Engineering / Technology from recognized university or Cleared Section A and B examination of Associate Membership of Institution of Engineers (India) or Cleared Section A and B examination of Aeronautical Society of India or Graduate membership examination of the Institute of Electronics and Telecommunication Engineers by actual studies
With a minimum of 60% marks or equivalent in the following disciplines

• Communication Engineering
• Computer Engineering / Technology
• Computer Engineering & Application
• Computer Science and Engineering / Technology
• Electrical and Computer Engineering
• Electrical and Electronics Engineering
• Electrical Engineering
• Electronics Engineering / Technology
• Electronics Science and Engineering
• Electronics
• Electronics and Communication Engineering
• Electronics and Computer Science
• Electronics and/ or Telecommunication Engineering
• Electronics and / or Telecommunication Engineering (Microwave)
• Electronics and computer Engineering
• Electronics Communication and Instrumentation Engineering
• Electronics Instrument & Control
• Electronics Instrument & Control Engineering
• Instrumentation & Control Engineering
• Instrument & Control Engineering
• Information Technology

Or Cleared section A and B examination of Aeronautical Society of India by actual studies With a minimum of 60% marks or equivalent in the following disciplines:-

• Aerospace Engineering
• Aeronautical Engineering
• Aircraft Maintenance Engineering
• Mechanical Engineering
• Mechanical Engineering and Automation
• Mechanical Engineering (Production)
• Mechanical Engineering (Repair and Maintenance)
• Mechatronics
• Industrial Engineering

As you are not Engineering Graduate you are not eligible to apply for AFCAT Ground Duty. However, you can apply for AFCAT Flying Branch and Ground Duty Non-Technical. And there is no specific requirement to Study Chemistry or Computer in B.Sc. SO you can take up any subject in B.Sc of your choice. To check the eligibility criteria for Flying branch and Ground Duty non technical use the link below

https://afcat.cdac.in/AFCAT/CareerAsPerBranches.html#mechanicalDiv