Final answer:
The pair CH₂CH₂OH(l) and H₂O(l) would form the most ideal solution because both engage in similar strong intermolecular hydrogen bonding forces. The correct answer is option 4.
Step-by-step explanation:
To determine which pair of liquids would form the most ideal solution, we look at the intermolecular forces and similarities in structure. An ideal solution is one where the intermolecular forces between unlike molecules are essentially the same as those between like molecules. Based on this definition and the examples provided, CH₂CH₂OH(l) and H₂O(l) would form the most ideal solution because both substances are capable of hydrogen bonding, which is a strong intermolecular force that would be prevalent in both pure substances and in the mixture. In comparison, the other pairs lack either similar structures or the ability to form hydrogen bonds with each other.