Materials existing as liquids have:

• A. Melting and boiling points above room temperature
• B. Boiling point and melting point same as room temperature
• C. Melting point and boiling point below room temperature
• D. None of the above

To determine the correct answer to your question about the properties of materials that exist as liquids, we need to consider the definitions of melting points and boiling points in relation to room temperature, which is typically around 20-25 degrees Celsius (68-77 degrees Fahrenheit).

Understanding Liquid States

Materials that are in a liquid state at room temperature have specific characteristics regarding their melting and boiling points. The melting point is the temperature at which a solid becomes a liquid, while the boiling point is the temperature at which a liquid turns into a gas.

Analyzing the Options

• A. Melting and boiling points above room temperature: This option suggests that both points are higher than room temperature. If this were true, the material would be solid at room temperature, not liquid.
• B. Boiling point and melting point same as room temperature: If both points were exactly at room temperature, the material would be in a state of equilibrium, potentially existing as both solid and liquid, but not definitively as a liquid.
• C. Melting point and boiling point below room temperature: This option indicates that both points are lower than room temperature. For a substance to be a liquid at room temperature, its melting point must be below room temperature, and its boiling point must be above room temperature.
• D. None of the above: This option implies that none of the previous statements accurately describe the properties of liquids.

Identifying the Correct Answer

For a material to exist as a liquid at room temperature, it must have a melting point that is below room temperature and a boiling point that is above room temperature. Therefore, the correct answer is:

C. Melting point and boiling point below room temperature

Examples for Clarity

Consider water, which is a common liquid. Water has a melting point of 0 degrees Celsius and a boiling point of 100 degrees Celsius. Since both of these points fit the criteria (melting point below room temperature and boiling point above room temperature), water remains a liquid at typical room temperatures.

In contrast, substances like ice (solid water) would not be classified as liquids at room temperature because their melting point is at 0 degrees Celsius, which is the threshold for transitioning to a liquid state.

Conclusion

In summary, for a material to exist as a liquid at room temperature, its melting point must be below room temperature, and its boiling point must be above it. Thus, the best choice from the options provided is C. Melting point and boiling point below room temperature.