I think it is A. The reaction rates can change.
I think we all know that B. and C. are incorrect, but I took a science lesson about this and it specifically said that on a graph of a rate, a curved line is NOT constant, meaning it is possible to not be constant.
The atomic number is the number of protons in the nucleus
Atomic number = protons
Protons = P Electrons = E P = E
Atomic mass = Neutrons + Protons
Atomic number = atomic mass = neutrons
P = E
AM - AN = N
Example:
Calcium = 20 Protons 20P = 20E
Atomic mass - atomic number = neutrons :)
Just divide 675 by the atomic number of cesium and you will end up with
5.078798426627975
