CIE iGCSE Co-Ordinated Science P2.2.2 Melting, boiling and evaporation Exam Style Questions Paper 1
Question
What are used as the fixed points on the Celsius scale of temperature?
▶️Answer/Explanation
Ans :A
Question
What happens to the temperature of a substance as it is melting and as it is boiling?
▶️Answer/Explanation
Ans : D
Question
A bowl of water is placed on a balance outside where it is sunny and windy. The reading on the balance is recorded.
After some time, the reading on the balance is less than the original reading.
Which statement explains why the reading is less?
(A) The water has become cooler.
(B) The water has become warmer.
(C) The water has condensed.
(D) The water has evaporated.
▶️Answer/Explanation
Ans: D
Question
A sample of liquid cools for 20 minutes. Its temperature is recorded every 2 minutes.
The results are shown.
How should the sample be described at the end of 18 minutes?
(A) all liquid
(B) all solid
(C) in the process of boiling
(D) in the process of solidifying
▶️Answer/Explanation
Ans: A
Question
Someone wearing wet clothes can feel cold even on a warm day.
Why do they feel cold?
(A) Water gives out heat as it evaporates.
(B) Water takes in heat as it evaporates.
(C) Water vapour gives out heat as it condenses.
(D) Water vapour takes in heat as it condenses.
▶️Answer/Explanation
Ans : B
Question
In a liquid-in-glass thermometer, which physical property of the liquid is used to measure temperature?
(A) colour
(B) mass
(C) pressure
(D) volume
▶Answer/Explanation
Ans : D
Question
Ice is taken from a freezer. After some time, the ice starts to melt. What is the temperature of the ice as it melts?
A. –10 °C
B. 0 °C
C. 20 °C
D. 100 °C
▶️Answer/Explanation
Answer: B. 0 °C
Explanation: Ice melts at 0 °C, which is the melting point of water. During the melting process, the temperature remains constant at 0 °C until all the ice has melted.
Question
A liquid starts to evaporate. Which molecules escape, and what happens to the temperature of the remaining liquid?
| molecules that escape | temperature of the remaining liquid | |
|---|---|---|
| A | less energetic | decreases |
| B | less energetic | increases |
| C | more energetic | decreases |
| D | more energetic | increases |
▶️Answer/Explanation
Answer: C
Explanation: During evaporation, the more energetic molecules escape from the liquid, leaving behind the less energetic ones. This results in a decrease in the temperature of the remaining liquid.
Question
A liquid-in-glass thermometer contains mercury. The thermometer is moved from cold water into hot water. What happens to the mercury?
A. It contracts.
B. It expands.
C. It freezes.
D. It melts.
▶️Answer/Explanation
Answer: B. It expands.
Explanation: Mercury expands when heated. When the thermometer is moved from cold water to hot water, the mercury inside the thermometer expands, causing the level to rise.
Question
The more energetic molecules of a liquid are escaping from its surface, causing the liquid to cool. What is happening to the liquid?
A. It is boiling.
B. It is condensing.
C. It is evaporating.
D. It is melting.
▶️Answer/Explanation
Answer: C. It is evaporating.
Explanation: Evaporation occurs when the more energetic molecules escape from the surface of a liquid, causing the liquid to cool.
Question
When evaporation occurs, molecules escape from the surface of a liquid. Which molecules escape, and what happens to the average speed of the molecules remaining in the liquid?
▶️Answer/Explanation
Answer: C
Explanation: During evaporation, the more energetic molecules escape from the surface of the liquid. This leaves the less energetic molecules behind, resulting in a decrease in the average speed of the remaining molecules.