Answer:
FeO
Step-by-step explanation:
FeO is the most basic oxide among the given options. This is because it only consists of one iron (Fe) atom and one oxygen (O) atom. In contrast, Fe₂O₃ has two iron atoms and three oxygen atoms, and FeO₄ consists of one iron atom and four oxygen atoms.
The basicity of an oxide is determined by the number of hydroxide ions (OH-) it can produce when dissolved in water. Basic oxides, also known as basic anhydrides, react with water to form hydroxide ions. Since FeO only has one oxygen atom, it can produce only one hydroxide ion when dissolved in water, making it the most basic oxide among the given options.
On the other hand, Fe₂O₃ and FeO₄ have more oxygen atoms, and therefore, they can produce more hydroxide ions when dissolved in water. However, it is worth noting that FeO₄ is not a valid formula for any known compound.