To me it looks like gas. Gas- CORRECT! Solid- incorrect because if this were a depiction of a solid then the particles would be much much closer together. Liquid - incorrect because the particles would be a little more crowded together. Plasma- I do not think that this answer is correct because, even though the spacing of particles is similar to the spacing of particles in plasma, the particles in plasma are charged particles(nuclei (+) and electrons(-)). Therefore, because the diagram doesn't have the particles labeled with charges, I believe that Plasma cannot be the correct answer.
To identify an atom, you simply need to look at the number of protons. This atom has 11 protons. On the periodic table, you can see that the element with 11 protons is sodium (Na).
