ISLAMAYA ENGLISH SCHOOL

Transcription

1 1 (a) Some water is poured onto a plastic table-top, forming a puddle. The same volume of water is poured into a plastic dish, which is placed alongside the puddle. This is illustrated in Fig water in puddle water in dish Both lots of water begin to evaporate. Fig. 7.1 In terms of the behaviour of molecules, describe what happens during the process of evaporation.... [2] Explain why the puddle dries out more rapidly than the water in the dish.... [2] (iii) State two changes that would make both lots of water evaporate more rapidly [2] 1 A W

2 3 (b) In a place where refrigeration is not possible, a person attempts to keep a bottle cool by using the procedure illustrated in Fig of milk damp cloth bottle milk water bowl Fig. 7.2 Explain in terms of molecules why this procedure would be successful [3] [Total: 9] 2 (a) Four identical metal plates, at the same temperature, are laid side by side on the The rays from the Sun fall on the plates. ground. One plate has a matt black surface. One plate has a shiny black surface. One plate has a matt silver surface. One plate has a shiny silver surface. State which plate has the fastest-rising temperature when the sunlight first falls on the plates... [1] (b) The apparatus shown in Fig. 4.1 is known as Leslie s Differential Air Thermometer. 2 A W

3 glass bulb painted matt black radiant heater shiny glass bulb T air liquid Fig. 4.1 The heater is switched off. Tap T is opened so that the air on the two sides of T has the same pressure. Tap T is then closed. The heater is switched on. On Fig. 4.1, mark clearly where the two liquid levels might be a short time later. [1] Explain your answer to (b).... [2] 3 The main parts of a cold store are shown in Fig cooling tubes cold store refrigeration unit Fig. 4.1 (a) Explain why the cooling tubes are positioned at the top of the store. 3 A W

4 [1] (b) Suggest why the refrigeration unit is outside the cold store [2] (c) The walls are made of thick thermally-insulating material. Why is it important to have the walls made like this? [2] (d) Even when the refrigeration unit is running continuously, there comes a time when the temperature in the store stops falling, and remains constant. Explain why this happens [2] [Total: 7] 4 A W

5 4 (a) Two students hang out identical T-shirts to dry at the same time in the same neighbourhood. The only difference between the drying conditions is that one T-shirt is sheltered from any wind and the other is in a strong breeze, as shown in Fig clothes line fence strong breeze no breeze Fig. 6.1 State and explain, in terms of water molecules, the difference between the drying times of the T-shirts [2] (b) Fig. 6.2 shows another occasion when a student hangs out two identical T-shirts to dry next to each other on a line. One T-shirt is folded double as shown in Fig clothes line Fig. 6.2 State and explain, in terms of water molecules, the difference between the drying times of the T-shirts. 5 A W

6 [2] (c) A runner in a hot country feels cooler if she pours water over her hair to keep it wet, even when the water is at the same temperature as the air around her. Explain, in terms of a change of state of water, why she feels cooler [2] 5 (a) The descriptions in the table below each give information about the molecules of a substance. In the space alongside each description, write the state of the substance being described. description The molecules are close together but not tightly-packed. They move around amongst each other. The molecules of the substance exert virtually no force on each other. They move around freely and fill their container. The molecules are tightly-packed. They have fixed positions, about which they can only vibrate. During these vibrations, they exert strong forces on each other. state of the substance [2] 6 A W

7 (b) Which word is used to describe what is happening when a solid turns to a liquid, without change of temperature, when a gas turns to a liquid, without change of temperature, (iii) when more molecules of a liquid are escaping from the surface than are returning to it? [3] 6 Fig. 4.1 shows a cross-section of a double-walled glass vacuum flask, containing a hot liquid. The surfaces of the two glass walls of the flask have shiny silvered coatings. silvered surfaces vacuum hot liquid (a) Explain Fig. 4.1 why the rate of loss of thermal energy through the walls of the flask by conduction is very low, 7 A W

8 why the rate of loss of thermal energy through the walls of the flask by radiation is very low. [3] (b) Suggest, with reasons, what must be added to the flask shown in Fig. 4.1 in order to keep the liquid hot [3] [Total: 6] 7 (a) On a hot day, sweat forms on the surface of a person s body and the sweat evaporates. Explain, in terms of the behaviour of molecules, the process of evaporation, how this process helps the body to cool down. 8 A W

9 [3] 8 The apparatus in Fig. 3.1 is being used to view the movement of some smoke particles trapped in a box. microscope light air molecules and smoke particles Fig. 3.1 (a) Describe what is seen when the smoke is viewed through the microscope [2] (b) In the space below, sketch how one smoke particle might move during a short interval of time. 9 A W

10 [2] (c) What causes the smoke particles to move? [2] (d) What name is used for this motion of the smoke particles? Complete the sentence. The motion of the smoke particles is known as... motion. [1] [Total: 7] 9 A metal tyre for a wooden wheel is made from an iron ring. This is shown in Fig wooden wheel iron ring joints Fig. 4.1 The iron ring is made slightly too small to fit on the wheel. (a) Explain why heating the iron ring will help it fit on the wheel [1] (b) Explain your answer to (a) in terms of the particles in the iron ring [2] (c) Explain what will happen to the iron ring after it has been fitted on the wheel and left to cool [1] (d) Suggest what happens to the joints in the wooden wheel after fitting the iron ring [1] [Total: 5] 10 A W

11 10 (a) A copper rod and a plastic rod each pass through holes in rubber bungs, so that their are inside a tank, as shown in Fig ends hot rubber water bung copper rod plastic rod Both rods are covered with wax. Fig. 5.1 Very hot water is poured into the tank, covering the end of each rod. What, if anything, is seen happening on the rods during the next few minutes? copper rod... plastic rod... [2] Explain your answers to (a) [2] (b) Explain, in terms of particles, how evaporation causes the hot water to cool [3] [Total: 7] 11 A W

12 11 Fig. 7.1 shows a domestic hot water system. to taps water metal storage tank jacket heater from water supply Fig. 7.1 (a) The heater is placed at the bottom of the storage tank. Name the process by which water in contact with the heater becomes hot.... [1] 1. Explain how the water at the top of the storage tank becomes hot. Include the word density in your answer [3] 2. State the name given to this process.... [1] (b) Hot water storage tanks are often covered in a material such as polystyrene or a jacket made from a woollen material. State the purpose of this covering.... [1] Suggest two reasons why the use of such a material is important [2] 12 A W