The diagram in image (4) in the image attached represents a sample of oxygen gas at stp.
Oxygen is a diatomic molecule, a diatomic molecule is a molecule that consists of only two atoms of the same element. In this case, the oxygen molecule consists of two oxygen atoms.
If we look at the diagram in the image attached very well, we will discover that the image in diagram (4) shows a molecule composed of two atoms of the same element and this fits exactly into the description of the oxygen molecule.
Learn more about diatomic molecules:
