When a gas bubbles through water, small droplets of water are usually picked up along for the ride and are mixed in with the gas above the water inside the eudiometer tube. The water vapor takes up room, but isn't the important gas that you need to measure. The table of water vapor is needed to subtract the unwanted water vapor from the collection of gases.
Answer:
Magnesium oxide = MgO
Iron = Fe
Iron (III) Oxide = Fe₂O₃
Magnesium = Mg
Skeleton equation = MgO + Fe ⇒ Fe₂O₃ + Mg
Mercury exist as liquid at normal earth tempertures
The answer is in the attachment below: