SAT Subject Chemistry vs Physics

I am not very good at either. I mean I made a 99 average in physics, but I do not feel like I understood the content very will (I am just a good test taker).

Is the Chemistry or Physics subject test easier? I am applying to Carnegie Mellon in either Engineering or Business and it requires Math II and a science.

“Easier” is relative. Get some prep books and take the practice exams. Whichever one you score higher on, that’s the one take.