Question 1

Based on the graph, which statement is most likely to be true?

Accepted Answer

D. It stops gaining heat at YZ.. At YZ the temperature stays constant at the higher level, indicating that although heat is being gained, the substance has finished its phase change and effectively stops gaining heat for further temperature change. The graph plateau at YZ shows no further temperature rise, so the ice (now water/vapour) stops gaining heat at YZ.

Question 2

Based on the graph, what were the states of ice in at VW and XY?

Accepted Answer

B. state at VW: solid; state(s) at XY: liquid & gas. At VW the ice is below 0 °C and rising in temperature, so it is still solid. At XY the temperature is rising again above 0 °C; this segment represents the boiling phase where the substance is changing from liquid to gas, so both liquid and gas are present.

Question 3

The table below shows the melting and boiling points of two substances, A and B. At what temperature would both substances A and B be in the solid state?

Accepted Answer

A. 13°C. A substance is solid when the temperature is below its melting point. For both A (melting point 15 °C) and B (melting point 23 °C) to be solid, the temperature must be below 15 °C. Only 13 °C satisfies this.

Question 4

An experiment was carried out using four glass beakers with the same amount of hot or cold water poured into each. Two of the beakers were then covered with a metal lid. Given that the experiment was conducted at room temperature, which one of the following correctly shows where water droplets would form after 3 minutes?

Accepted Answer

C. Beaker of cold water at 5°C covered with a metal lid, with water droplets on the outside of the beaker.. Water droplets form by condensation when warm water vapour in the air loses heat upon contact with a cold surface. The beaker of cold water at 5°C has a cold outer surface; water vapour from the surrounding warm room air condenses on its cold outer surface, forming water droplets. Whether or not the cold beaker has a metal lid does not change condensation on its outer wall, but option (3) correctly depicts droplets on the outside of the cold (5°C) beaker.

Question 5

Ali carried out an experiment using three identical tanks, A, B and C. He filled each tank with an equal amount of water and then placed a foam board in each one. The foam boards were of different sizes and floated on the surface of the water as shown in the diagram below. After two days, Ali recorded the volume of water left in each tank. Which of the following shows the correct arrangement of the volume of water in the tanks from the least to the most?

Accepted Answer

A. least → most: A, C, B. Evaporation rate depends on the exposed water surface area. Tank A has the smallest foam board, leaving the largest exposed water surface and therefore the fastest evaporation (least water remaining). Tank B has the largest foam board covering most of the surface, so evaporation is slowest (most water remaining). Tank C is in between. So from least to most: A, C, B.

Question 6

Robert placed a torch at position F and an object at position D to cast a shadow on the screen as shown below. Which of the following actions will result in a larger shadow being cast on the screen?

Accepted Answer

C. Move the screen to A.. A shadow becomes larger when the screen is moved further from the object (away from the light source) because the diverging light rays spread out more before hitting the screen. Moving the screen from its current position to A (further from the object/torch) increases the screen-to-object distance and so produces a larger shadow.

P5 Science SA1 2025 — Anglo Chinese

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