Before recycling, plastics are sorted according to their resin identification code, which was developed by the Society of the Plastics Industry in 1988. Presorting is necessary, because of the following physical and chemical characteristics of polymers:
I. Polymers have a tendency to phase-separate when molten.
II. Different polymers have very different decomposition temperatures.
III. Polymers featuring very high melting temperatures decompose into smaller molecules at high temperatures rather than melt.
IV. Molten polymers mix easily.

Question

Quizplus · Accepted Answer

The statement identifies four physical and chemical characteristics of polymers, and according to the statement, all four characteristics are reasons why plastics need to be sorted before recycling. Therefore, the best choice is C, which includes all four characteristics.

Before Recycling, Plastics Are Sorted According to Their Resin Identification