Answer:
c. 19
Explanation:
Potassium is a chemical element of the periodic table whose chemical symbol is K, whose atomic number is 19. It is an alkaline metal of white-silver color, which abounds in nature in the elements related to salt water and other minerals. It oxidizes rapidly in air, is very reactive, especially in water, and chemically resembles sodium. It is an essential chemical element.
The K having an atomic number of 19 means that it has 19 protons and in normal conditions for a neutral atom it will have 19 electrons, and being one step away from argon gas makes it extremely unstable.
