How are all atoms similar?

Atoms are similar in the way that their nuclei contain only protons and neutrons.

All things are made of atoms, and all atoms are made of the same three basic particles - protons, neutrons, and electrons. But, all atoms are not the same. The difference in the number of protons and neutrons in atoms account for many of the different properties of elements.

I hope this helps :)

it should be all of them because it asks if you included all of those in your answer

explanation:

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.