A variable is not consistent or having a fixed pattern; liable to change.
Answer:
Na
Explanation:
sodium has mass number 23 and atomic number 11 so number of protons =number of electrons =atomic number which is 11 and number of neutrons=mass number-number of protons =23-11=12
The number in isotope platinum-194 stands for the <em>total </em>amount of protons and neutrons. In other words, this is the mass. =)
