Final answer:
Molybdenum (Mo) is most likely to form an oxide with the formula MO3 due to its tendency to form higher oxidation state oxides (c).
Step-by-step explanation:
The element most likely to form an oxide with the formula MO3 is molybdenum (Mo). This prediction is based on the general chemical behavior of transition metals and their common oxidation states. Molybdenum tends to form higher oxidation state oxides such as MoO3, which is molybdenum trioxide, a well-known compound. In contrast, zirconium (Zr) and niobium (Nb) typically do not form MO3 oxides under standard conditions.
The element most likely to form an oxide with the formula MO₃ is Mo. The reason behind this is that Mo belongs to the group 6 of the periodic table, while Zr and Nb belong to the group 4 and 5, respectively. Group 6 elements have a higher tendency to form higher oxidation states compared to group 4 and 5 elements. Therefore, Mo is more likely to form an oxide with the formula MO₃.