Answer
(b)
Work Step by Step
The first diagram is one of two different gases mixed together. We can see that there are two gases here because each gas is represented by a different colored sphere. We know that these gases are in the gaseous state because they are floating freely, which is what gas particles do.
In the second diagram, the two gases have combined together in a compound because in each pair of molecules are two different colored spheres representing the two different elements. We know that the two gases have combined to make a compound in the solid state because the spheres are in a fixed volume.
This scenario corresponds to option (b).
