CIE iGCSE Co-Ordinated Science P2.2.2 Melting, boiling and evaporation Exam Style Questions Paper 1
▶️ Answer/Explanation
During evaporation, the more energetic particles escape from the surface of the liquid, which means the remaining liquid has fewer particles (mass decreases) and the average kinetic energy of the remaining particles decreases, causing the temperature to decrease. This is why evaporation causes cooling. Row A correctly shows both mass and temperature decreasing.
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
During evaporation, particles at the surface of a liquid with the highest kinetic energy (the more energetic ones) overcome the intermolecular forces holding them in the liquid and escape as a gas. The remaining particles have lower average kinetic energy, causing the liquid to cool. The least energetic particles do not have enough energy to escape.
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
Condensation is the change of state from gas to liquid (e.g. water vapour turning into liquid water). In the diagram, arrow A shows this transition. The other arrows represent melting, boiling, or freezing.
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
During evaporation, the most energetic water particles escape from the liquid surface as vapour.
These particles take their kinetic energy with them, which is drawn as heat energy from the skin and remaining liquid, lowering their temperature.
Since evaporation takes in heat from its surroundings (the person’s skin), the person feels cold.
✅ Answer: (B)
These particles take their kinetic energy with them, which is drawn as heat energy from the skin and remaining liquid, lowering their temperature.
Since evaporation takes in heat from its surroundings (the person’s skin), the person feels cold.
✅ Answer: (B)
▶️ Answer/Explanation
During solidifying, the temperature would stay constant (a plateau) at the freezing point while both liquid and solid are present.
The recorded temperatures fall steadily throughout the 20 minutes with no plateau, showing that solidifying has not begun.
At 18 minutes the sample is therefore still cooling as a liquid, not solidifying or boiling.
✅ Answer: (A)
The recorded temperatures fall steadily throughout the 20 minutes with no plateau, showing that solidifying has not begun.
At 18 minutes the sample is therefore still cooling as a liquid, not solidifying or boiling.
✅ Answer: (A)