Question

Potassium has a mass number of 40 and an atomic number of 19. How many protons does it have?

A.59
B.21
C.19
D.40

Answer 1

The answer is C.
Potassium-40 or any type of potassium always has an atomic number 19 and 19 protons. 

Answer 2

The answer is c. 19


The atomic number always represents number of protons