Answer
(a) This diagram depicts a single element in the liquid phase.
(b) This diagram depicts diatomic molecules of two different gases.
Work Step by Step
(a) This diagram depicts a single element in the liquid phase. The balls are of a single color, denoting a single element. The balls are arranged in a line, so they are packed tightly, but they are able to slide around.
(b) This diagram depicts diatomic molecules of two different elements. There are two different elements, represented by the two differently colored balls. The red balls are grouped in pairs, which is the same for the blue balls, meaning that the atoms of each element form diatomic molecules. The two elements are in the gaseous state because they are floating freely in the air.