The eligibility criteria for Merchant Navy is that you should pass your 10+2 with PCM and have at least 55% marks in your 10+2. Normal vision is preferred but glasses upto +2.5 or -2.5 is allowed.

As you didn't have Physics you aren't eligible for Merchant Navy examinations.

To know more about Merchant Navy visit the link below:

https://www.careers360.com/careers/merchant-navy

I hope this answer helps. All the very best for your future endeavors!