Question 1:
What is the critical point on a phase diagram?
Explanation: The correct answer is C) The temperature and pressure at which a substance exhibits properties of both liquid and gas phases. The critical point on a phase diagram is the specific temperature and pressure at which a substance can exist in equilibrium as both a liquid and a gas. Above this critical point, the distinction between the liquid and gas phases becomes indistinguishable, and the substance exhibits properties of both phases.
Question 2:
What is the triple point on a phase diagram?
Explanation: The correct answer is C) The temperature and pressure at which all three phases of a substance coexist in equilibrium. The triple point on a phase diagram is the specific temperature and pressure at which all three phases (solid, liquid, and gas) of a substance can coexist in equilibrium. It represents the unique combination of conditions where all three phase boundaries intersect.
Question 3:
What happens to the boiling point of a substance as pressure decreases?
Explanation: The correct answer is B) The boiling point decreases. As pressure decreases, the boiling point of a substance decreases. This is because the boiling point is the temperature at which the vapor pressure of the substance equals the atmospheric pressure. When the external pressure is reduced, less energy is required for the vapor pressure to equal the lower pressure, resulting in a lower boiling point.
Question 4:
Which phase transition is associated with an increase in entropy?
Explanation: The correct answer is B) Sublimation. Sublimation is the phase transition in which a substance changes directly from the solid phase to the gas phase without passing through the liquid phase. It is associated with an increase in entropy because the gas phase typically has higher entropy than the solid phase.
Question 5:
What is the phase transition called when a substance changes directly from a gas to a solid without passing through the liquid phase?
Explanation: The correct answer is D) Deposition. Deposition is the phase transition in which a substance changes directly from the gas phase to the solid phase without passing through the liquid phase. It occurs when the temperature and pressure conditions allow the gas molecules to lose enough energy to form a solid directly.This process is commonly observed when water vapor in the air comes into contact with a cold surface and forms frost or snow.
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