I wouldn't advise going into a computer science degree with no, or little previous knowledge. it's not a requirement to know any computer science, but to be completely honest I don't know why. the first classes are often taught extremely terribly, because they're people who have been coding since they started using they started counting past ten and using their times tables, then they're people who don't have a clue what's going on and the teacher just thinks they're teaching it well and your not putting in enough effort, but nonetheless. those subjects should be good, honestly maths by itself would have probably done the job well enough, physics can be useful for very specific topics in AI but you can probably just learn that stuff as you go tbh. if your enjoying chemistry then I would definitely say keep it as a subject, but if you're not so much, then change it. if you're curious wether you would like computer science don't focus on the math, component since you already seem comfortable with math, focus on the coding, and don't watch YouTube videos for that go to freeecodecamp or smth, it's a waste of time learning how to code in a passive way. just like it's a waste of time, doing the same in maths.