Final answer:
The equation that represents reduction of molybdenum is MoO₂ + 4 H₂ → Mo + 2H₂O.
Step-by-step explanation:
The correct equation that represents reduction of molybdenum is option 2) MoO₂ + 4 H₂ → Mo + 2H₂O.
In this equation, molybdenum is being reduced because it is changing from a higher oxidation state (+4) in MoO₂ to a lower oxidation state (0) in Mo.
The reaction is balanced because both sides of the equation have the same number of each type of atom.