Unequal Pair(s) Explanation:

Physical Address - MAC Address:
- A physical address refers to the unique identifier assigned to a network interface card (NIC) by the manufacturer.
- MAC address stands for Media Access Control address, which is a type of physical address.
- These addresses are typically hardcoded into the NIC and cannot be changed.
- Both terms refer to the same concept, so they are equal and not an unequal pair.

IP Address - Logical Address:
- An IP address is a numerical label assigned to each device connected to a computer network.
- It serves two main functions: identifying the host or network interface and providing the location of the host in the network.
- A logical address is a broader term that encompasses various types of addresses used in networking, including IP addresses.
- Therefore, IP address is a specific type of logical address, and they are not an unequal pair.

Ethernet - IEEE802.4:
- Ethernet is a widely used networking technology commonly used for local area networks (LANs).
- It defines the physical and data link layers of the OSI model.
- IEEE 802.4 is a standard that defines another type of LAN technology known as Token Bus.
- Ethernet and IEEE 802.4 are two different and incompatible LAN technologies, making them an unequal pair.

Serial port - COM1:
- A serial port is a physical interface used for connecting devices, such as printers, modems, and serial communication devices, to a computer.
- COM1 is a specific designation for the first serial port on a computer system.
- Serial port and COM1 are two terms that refer to the same concept, so they are equal and not an unequal pair.

In conclusion, the unequal pair in the given options is Ethernet - IEEE802.4.