Answer:
To identify the physical states of substances X, Y, and Z at room temperature (30°C), we need to compare the given melting and boiling points with the temperature of 30°C.
Substance X:
- Melting Point: -219°C
- Boiling Point: -183°C
At 30°C, which is higher than the boiling point of -183°C for substance X, it would be in a gaseous state.
Substance Y:
- Melting Point: 119°C
- Boiling Point: 445°C
At 30°C, which is lower than the melting point of 119°C for substance Y, it would be in a solid state.
Substance Z:
- Melting Point: -15°C
- Boiling Point: 78°C
At 30°C, which is within the range between the melting point of -15°C and boiling point of 78°C for substance Z, it would be in a liquid state.
Therefore, at room temperature (30°C), substance X would be a gas, substance Y would be a solid, and substance Z would be a liquid.