Question

select the common name for the ether.
the common name is:
○ ethyloxy cyclopentyl ether
○ cyclopentyl ethyl ether
○ ethyl cyclopentyl ether
○ cyclopentoxy ethyl ether

Explanation:

In the common - naming of ethers, we name the two alkyl (or aryl) groups attached to the oxygen atom. The general format is “(smaller group)(larger group)ether”. Here, the two groups are ethyl ($-C_2H_5$) and cyclopentyl ($-C_5H_9$). When naming, we list the groups in alphabetical order. “Cyclopentyl” comes before “ethyl” alphabetically. Also, in the common naming of ethers, we do not use the “-oxy” suffix for the alkyl group when it is part of the two - part name (the “-oxy” suffix is used in the IUPAC systematic naming for the alkoxy group when the ether is named as an alkane with an alkoxy substituent).

Answer:

cyclopentyl ethyl ether