Question

A compound, X, has a melting point of 71 °C and a boiling point of 375 °C. Which statement about X is correct?
A) It is a liquid at 52 °C and a gas at 175 °C.
B) It is a liquid at 69 °C and a gas at 380 °C.
C) It is a liquid at 75 °C and a gas at 350 °C.
D) It is a liquid at 80 °C and a gas at 400
Please answer quickly! ​

Answer 1

Answer:

D) It is a liquid at 80 °C and a gas at  400°C

Explanation:

Because after melting solid converted to liquid >71 and after boiling it transfers  to gas > 375

Answer 2

The correct option is (D)

Explanation:

• The melting point of a pure substance at atmospheric pressure is the temperature at which the solid and liquid phases are at equilibrium.
• After the melting point as the temperature increases, the concentration of liquid starts increasing, and that of solid decreases. Thus, the substance exists more in the liquid state.
• The boiling point of a pure substance at atmospheric pressure is the temperature at which the liquid and vapours are at equilibrium.
• As the temperature is increased beyond the boiling point, more vapours start forming and the substance exists in a gaseous state.
• In the given question, the melting point of the compound X is 71°C. As the temperature increases, X will exist as a liquid.
• The boiling point of X is 375°C. Thus, It will exist as a gas above 375°C.
• Therefore, X exists as a liquid at 80°C and as a gas at 400°C. Hence, the correct option is (D).