Final answer:
For the molecule AX4E, which has four bonded atoms and one lone pair represented by 'E', the total number of electron domains is 5, corresponding to the bonding pairs and the lone pair combined.
Step-by-step explanation:
The molecule described as AX4E refers to a central atom 'A' with four atoms 'X' bonded to it and one lone pair 'E'. In this notation, the letter 'A' represents the central atom, 'X' represents atoms bonded to the central atom, and 'E' represents a lone pair of electrons on the central atom. The total number of electron domains, which include both bonding domains and lone pairs, determines the electron geometry of the molecule.
To count the electron domains, you simply add the number of bonding pairs (represented by the number next to 'X') to the number of lone pairs (represented by the number next to 'E'). In this case, AX4E has 4 bonding domains from the four 'X' atoms and 1 lone pair 'E', leading to a total of 5 electron domains around the central atom.
Therefore, the correct answer is 3) 5 electron domains.