The State of Substances based on Melting and Boiling Points:

To determine the state of a substance based on its melting and boiling points, we need to understand the different states of matter and their corresponding temperature ranges. The three common states of matter are solid, liquid, and gas. Let's analyze each substance given and determine their states based on their melting and boiling points.

1. Substance X:
- Melting Point: -219 degrees Celsius
- Boiling Point: -183 degrees Celsius

The melting point of substance X is lower than its boiling point. Additionally, both the melting and boiling points are below 0 degrees Celsius. Based on these factors, we can conclude that substance X is in a solid state at room temperature. It remains solid until it reaches its melting point, at which it will transition into a liquid state. When the temperature exceeds its boiling point, it will vaporize and become a gas.

2. Substance Y:
- Melting Point: 119 degrees Celsius
- Boiling Point: 445 degrees Celsius

The melting point of substance Y is higher than its boiling point. Both the melting and boiling points are above 0 degrees Celsius. From this information, we can infer that substance Y is a solid at room temperature. When heated to its melting point, it will transform into a liquid, and upon reaching its boiling point, it will vaporize and become a gas.

3. Substance Z:
- Melting Point: -15 degrees Celsius
- Boiling Point: 78 degrees Celsius

Substance Z has a melting point below 0 degrees Celsius and a boiling point above it. This indicates that substance Z is a solid at room temperature. When the temperature rises above its melting point, it will transition into a liquid state. As the temperature continues to increase, it will eventually reach its boiling point and convert into a gas.

Summary:
1. Substance X: Solid at room temperature, melts into a liquid below -219 degrees Celsius, and boils into a gas above -183 degrees Celsius.
2. Substance Y: Solid at room temperature, melts into a liquid above 119 degrees Celsius, and boils into a gas above 445 degrees Celsius.
3. Substance Z: Solid at room temperature, melts into a liquid below -15 degrees Celsius, and boils into a gas above 78 degrees Celsius.

Remember, these conclusions are based solely on the given melting and boiling points and assume standard pressure.

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