Question

which of the following is in a liquid state at temperatures between −100 °c and 78 °c and in a gaseous state at temperatures above 78 °c? answer options: select one of four mercury alcohol water acid

Explanation:

To solve this, we analyze the boiling and melting points of each substance:

• Mercury: Melting point ~ -38.83°C, boiling point ~ 356.73°C. Doesn't match the 78°C boiling point.
• Alcohol (ethanol): Melting point ~ -114°C, boiling point ~ 78°C. So between -100°C (above melting point) and 78°C (below boiling point) it's liquid; above 78°C, gaseous.
• Water: Melting point 0°C, boiling point 100°C. Doesn't match 78°C boiling point.
• Acid: A general term, but common acids like sulfuric acid have much higher boiling points. Ethanol (alcohol) fits the given temperature range for state changes.

Answer:

B. Alcohol