Simple chemistry question please help. Look at image.

It's the last one. They all have the same number of electrons in their outer ring. They're also called valence electrons.

Hope this helped!

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.