P5 Science CA2 2025 — Pei Chun

Jane poured different volumes of water at different temperatures into three identical beakers, W, X and Y, as shown below. Which of the following statements is true?

Luke was holding a metal straw dipped in a glass of iced water. After some time, he felt that the metal straw was cold. Which of the following correctly explains why Luke felt that the metal straw was cold?

Keith has two metal bottles, A and B, made of the same type of metal. Bottle A has a thick metal wall while bottle B has air in between the two metal walls. Keith wants to keep his fruit juice cold in a bottle. Which of the following shows the correct choice of bottle and the reason?

The table below shows the melting and boiling points of substances P and Q. Which of the following shows the correct states of substances P and Q at 30 °C?

Siti wanted to find out how the temperature of water affects the rate of evaporation. Which two set-ups should Siti use for her investigation?

The diagram below shows the water cycle. Which of the following correctly shows where condensation and evaporation occur?

The diagram below shows a model of the human respiratory system. When the rubber sheet is pulled down, air enters the balloon and the balloon expands. Which parts do the balloon and straw represent?

Aylssa prepared two similar set-ups, P and Q, as shown in the diagram. She watered both pots of plant with the same amount of water and placed them in the sun for a few hours. Which of the following correctly shows the change in the amount of oxygen in both set-ups?

Junjie set up an experiment using three similar leaves, A, B and C. These leaves have more tiny openings on their bottom surfaces than on their top surfaces. Leaves lose water through these tiny openings. He coated some surfaces of the leaves with oil that did not drip. Each leaf was weighed and then hung in an open area as shown below. After five hours, each leaf was weighed again and the loss of mass was recorded. Which one of the following shows the loss of mass for A, B and C?

Five people were trapped in a small lift for 15 minutes. There was very little fresh air entering the lift. (a) The amount of carbon dioxide in the lift increased after some time. Explain why. [1] (b) The graphs below show the changes in the amounts of two gases (other than carbon dioxide) in the lift. Name the two gases. gas A: ____ gas B: ____ [2]

Thad conducted an experiment to compare the effect of heating different metals. He heated three rods made of metals K, L and M for 20 minutes. He measured the lengths of the three rods before and after the heating. His results are shown below. Metal K: 150 → 157 mm; Metal L: 150 → 160 mm; Metal M: 150 → 152 mm. (a) Other than the length of the rod before heating, state one other variable of the rods that should be kept the same so that the experiment was a fair test. [1] (b) State how the mass of the rods would be affected by the heating. [1] (c) A bridge made of metal L has gaps at its ends to prevent it from bending on a hot day. Explain how having the gaps can prevent the bridge from bending. [1]

(a) State what boiling means. [1] (b) Ravi heated some water in a glass pot. After a while, he observed bubbles in the water and white fumes as shown. Explain how the white fumes were formed. [2] (c) Identify the state of water of the white fumes. [1]

Caili set up the experiment using two identical cups and two identical pots as shown below. She filled both pots with the same amount of sand and added water to the sand in set-up A. She placed both set-ups in a hot and dry place and recorded the temperature of the air inside each set-up. Results: At 0 min — Set-up A: 30°C, Set-up B: 30°C; at 10 min — A: 28°C, B: 30°C; at 20 min — A: 27°C, B: 30°C. (a) Suggest how the water in the wet sand helped in lowering the temperature of the air in set-up A. [1] (b) Caili repeated her experiment with a larger pot, using the same amount of sand and water as in set-up A. She observed that the temperature of the air in set-up C was lower than that in set-up A after 20 minutes. Explain her observation. [1]