Substance Melting point / °C Boiling point / °C nitrogen −210 −196 oxygen −218 −183 mercury −39 357 sodium 98 883 The table gives the melting point and boil...
Question 1 Report
| Substance | Melting point / °C | Boiling point / °C |
|---|---|---|
| nitrogen | −210 | −196 |
| oxygen | −218 | −183 |
| mercury | −39 | 357 |
| sodium | 98 | 883 |
The table gives the melting point and boiling point of four pure substances. Room temperature is 20 °C. Using the data, which one of these substances is a liquid at room temperature?
Answer Details
A substance is a liquid at a given temperature only if that temperature is above its melting point but below its boiling point.
At 20 °C, mercury qualifies because its melting point is −39 °C (below 20) and its boiling point is 357 °C (above 20), so 20 °C lies within its liquid range.
Sodium melts at 98 °C, so at 20 °C it is still solid; nitrogen (boiling point −196 °C) and oxygen (boiling point −183 °C) have already boiled to gas well below 20 °C, so none of those is liquid at room temperature.
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