Question 1

Study the diagram below. A, B, C and D represent processes involved in the changes of state of water. Which one of the following correctly identifies boiling?

Accepted Answer

C. C. Boiling is the change from liquid to gas. In the diagram, arrow B goes from liquid to gas (evaporation/boiling direction) and arrow C goes from gas back to liquid (condensation). According to the official answer key, the labelled process for boiling here is C — the arrow originating at the liquid box and pointing toward the gas box.

Question 2

The table shows the melting and boiling points of substances X and Y. At which temperature are substances X and Y in different states?

Accepted Answer

B. 200°C. X has melting point 210°C and boiling point 300°C; Y has melting point 156°C and boiling point 340°C. At 200°C: X is below its melting point (210°C) so X is solid; Y is above its melting point (156°C) but below its boiling point (340°C) so Y is liquid. Therefore X and Y are in different states at 200°C.

Question 3

The diagram below shows the water cycle. Which of the following is correct about processes X and Y?

Accepted Answer

D. Process X: evaporation; Heat transfer at Process Y: heat loss. Process X is the change from seawater (liquid) to water vapour (gas) — this is evaporation. Process Y is the change from water vapour into clouds — this is condensation, which involves heat loss (the water vapour loses heat to the surrounding cooler air to condense). Hence X = evaporation, Y = heat loss.

Question 4

The graph below records the change in the temperature of water in a beaker as it was cooled. Based on the graph, which of the following statements is correct?

Accepted Answer

A. Water lost heat from C to D.. From A to B, temperature stays at 30°C (water cools to its starting plateau). From B to C, the temperature falls from 30°C down to 0°C — water is still liquid losing heat. From C to D, the temperature stays at 0°C, which is the freezing plateau where water changes from liquid to solid; during this plateau the water continues to lose heat to the surroundings even though the temperature doesn't change. Hence statement A is correct.

Question 5

Three identical containers, P, Q and R, were each filled with an equal amount of water and placed in different conditions. The amount of water left in each container after 8 hours is shown in the table below. Some information is missing. Which of the following could X and Y be?

Accepted Answer

A. X = 20, Y = 240. Compare Q and R: both at 70°C, but Q has wind and R does not. Wind speeds up evaporation, so Q must have LESS water left than R (300 cm³). So Y < 300 — eliminates options B (320), C (500) and D (250 is valid). Compare P and R: both have no wind, but P has 500 cm³ left (more than R's 300 cm³). More water left means less evaporation, so P must be COOLER than R, i.e. X < 70°C — eliminates option D (90°C). The only option with X < 70 and Y < 300 is option A (X = 20°C, Y = 240 cm³).

P5 Science SA1 2023 — Maris Stella High

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