The diagram shows a section of a polymer - HSC - SSCE Chemistry - Question 6 - 2010 - Paper 1

To identify the systematic name of the monomer, we first analyze the structure shown in the diagram. The polymer has repeating units containing a benzene ring attached to an ethylene unit ( C=C ext{, with hydrogen atoms connected to the carbons} ).

Given the options:

• Polybenzene refers to a polymer made solely from benzene, which is not accurate here as the monomer contains an ethylene group.
• Benzylethene implies a benzene ring attached to an ethylene group, which does not correspond to the structure seen.
• Ethylbenzene consists of an ethyl group attached to a benzene ring, but does not match the polymer's structure production here.
• Ethenylenebenzene correctly describes a compound with both the ethylene and benzene units.

Thus, the correct systematic name of the monomer is Ethenylenebenzene (D).