Yeah it uses some valuable scientific vocabulary and background knowledge, I hope this hypothesis will be good enough for your teacher (don't worry it will be)
Ca because it has a larger atomic radius.
Answer: The answer is A. - 4.88x10^20 H2O2 molecules
Explanation: I hope this helps!
Density = mass / volume
Density = (78g) / (23cm^3)
Density = 3.4g/cm^3
