I did all of the modules that are in core science AQA (B1, C1, P1) and got an A* in each of them. Although, they were my lowest UMS scores across triple science so I would have only just got an a* if I did core
B1: 91/100 C1: 91/100 P1: 90/100
B2: 93/100 C2: 93/100 P2: 100/100
B3: 100/100 C3: 100/100 P3: 100/100
So, weirdly it is harder to get an A* in core than in each science (Chem, Phys, Bio) in triple.