What distinguishes low density poly(ethene) from high density poly(ethene) in terms of structure?

The distinguishing factor between low density poly(ethene) and high density poly(ethene) primarily revolves around the arrangement and structure of the polymer chains. Low density poly(ethene) (LDPE) is characterized by significant branching in its molecular structure. This branching leads to a more random and less crystalline arrangement, which contributes to its flexibility and lower density.

In contrast, high density poly(ethene) (HDPE) has a more linear structure with less branching. This allows the polymer chains to pack more closely together, resulting in a higher degree of crystallinity. The closely packed chains in HDPE give it higher strength and density compared to the more irregular structure of LDPE.

Thus, the correct choice highlights that low density poly(ethene) is defined by the random arrangement of branches, which is a direct result of its branched structure, differentiating it from high density poly(ethene).