In this example it says a double gas fluoride is a colorless crystalline solid at room temperature. Which one of the following is the most likely formula of this compound?
So here it's a fluoride. All these examples are fluorides. It exists as a crystalline solid at room temperature, which indicates it's pretty stable. And we know that out of all the noble gases, it's xenon that helps to make stable compounds, and it makes stable compounds with fluorine.
If we take a look, the only option that possesses xenon in the formula is option D. Here we have xenon tetrafluoride as this stable colorless crystalline solid found at room temperature.