Final answer:
At -104°C, higher than the boiling point of -109°C, the substance in question would be in the gas phase, as temperatures above the boiling point indicate the substance exists as a gas.
Step-by-step explanation:
If a substance has a melting temperature of -200°C and a boiling temperature of -109°C, it means that the substance will be in different states at temperatures within this range. Specifically, at -104°C, which is a higher temperature than the boiling point of -109°C, the substance would be in the gas phase. This is because any temperature above the boiling point indicates that the substance will exist as a gas, just as any temperature below the melting point indicates that it would be a solid. If this substance were between -200°C and -109°C, it would be in the liquid state. Phase transitions such as melting and boiling are indicators of a substance changing from one state to another, such as from liquid to gas, which occurs at the boiling point.