CIE iGCSE Co-Ordinated Science P2.2.2 Melting, boiling and evaporation Exam Style Questions Paper 3
Question
(a) Fig. 12.1 shows an electric heater used in a classroom in a school.
The air around the heater is warmed.
(i) On Fig. 12.1 draw three more arrows to show how the warmed air moves around the classroom.
One arrow has been drawn for you.
(ii) State the name of the method of thermal energy transfer you have drawn in (a)(i).
(b) The teacher in the classroom measures the temperature in the room with a thermometer.
Fig. 12.2 shows the thermometer.
(i) State the name of the temperature scale used on the thermometer.
(ii) State the name of a liquid that is used in thermometers.
(iii) State the physical property of the liquid that varies with temperature.
(c) (i) In the school an electric bell rings to show that the lesson has ended.
The bell makes sound waves that travel through the air.
Sound waves cannot travel through a vacuum.
Explain why sound cannot travel through a vacuum.
(ii) Inside the electric bell there is a solenoid.
The solenoid coil is shown in Fig. 12.3.
On Fig. 12.3, draw the pattern of the magnetic field that is produced when an electric current passes through the solenoid as shown.
▶️Answer/Explanation
Ans : 12(a)(i) arrow
across the top
then dropping down
then left to right along floor
1 mark for any one correct arrow ;
1 mark for all three arrows correct ;
12(a)(ii) convection ;
12(b)(i) celsius ;
12(b)(ii) alcohol or mercury ;
12(b)(iii) volume / density ;
12(c)(i) There is no medium (for the propagation of the sound wave) ;
12(c)(ii) at least two lines going all the way through coil ;
line curving upwards and line curving downwards ;
Question
(a) The two boxes on the left each contain the name of an energy resource.
The four boxes on the right contain advantages or disadvantages of the energy resources.
Draw two lines from each energy resource to the advantages or disadvantages of the energy resource.
(b) The statements, A to E, describe processes in a coal-burning power station.
They are not in the correct order.
A Coal burns to produce thermal energy.
B A turbine drives a generator.
C Steam is produced.
D Steam turns a turbine.
E Thermal energy boils water.
(i) Use the letters B to E to complete the sequence to describe how the power station generates electricity.
A $\underset{}{\rightarrow}$ …………. $\underset{}{\rightarrow}$ ………….$\underset{}{\rightarrow}$ ………….$\underset{}{\rightarrow}$ …………$\underset{}{\rightarrow}$ electricity is generated
(ii) State the boiling point of water.
(c) When coal is burned in a power station, the energy in the coal is transferred to the energy outputs shown in Table 9.1.
The energy outputs are shown as percentages of the total energy from the coal.
(i) Explain why Table 9.1 shows that energy is conserved in the processes in the power station.
(ii) The power station in Table 9.1 produces a lot of thermal energy.
Explain why the power station is not efficient.
(d) The electricity generated from the power station is supplied to a house to power the lighting circuit.
Lamps for lighting in the house are connected in a parallel circuit and not in a series circuit.
(i) Complete the circuit diagrams to show the difference between a series circuit and a parallel circuit.
Use two lamps in each circuit.
ii) State one advantage of connecting lamps in parallel in a lighting circuit.
▶️Answer/Explanation
Ans : 9(a) coal to non-renewable and polluting ;
geothermal to renewable and non-polluting ;
9(b)(i) A → E → C → D → B
E and C correct ;
D and B correct ;
9(b)(ii) 100(°C) ;
9(c)(i) numbers add up to a hundred ;
9(c)(ii) thermal energy is not useful / useful energy output is only 25% ;
9(d)(i) correct symbol for lamp ;
series circuit correct ;
parallel circuit correct ;
9(d)(ii) any one from :
all the lamps can be switched on independently
all lamps get full mains voltage
if one lamp fails the others can still work…
Question
(a) α-particles, β-particles and γ-rays are all used in hospitals to treat cancer.
Table 6.1 gives information about the nature and charge of these three radiations.
(i) Complete Table 6.1.
(ii) Place the three radiations in order of their ionising ability, from most ionising to least ionising.
(iii) State which radiation is the most penetrating.
(b) X-rays and ultrasound waves are also used in hospitals.
(i) State one use of X-rays in hospitals.
(ii) Ultrasound waves have a frequency that is too high for a human to hear.
Use your knowledge of the range of audible frequencies for a human to suggest the frequency of ultrasound waves.
(c) A doctor in the hospital uses some sanitising hand liquid. The liquid contains ethanol, which evaporates from the skin of the doctor and cools the doctor’s hands.
Explain why the evaporation of the ethanol causes the doctor’s skin to cool.
Use ideas about molecules in your answer.
▶️Answer/Explanation
Ans : 6(a)(i)
;;;
one mark for each correct row
6(a)(ii) (in order)
$\alpha$ (-particles)
β (-particles)
$\gamma$ (-rays);
6(a)(iii) $\gamma$ -rays ;
6(b)(i) scanning / imaging (tissues) inside the body ;
6(b)(ii) any value above 20 000 (Hz) ;
6(c) most energetic molecules escape ;
from surface of liquid ;
lowering the temperature of the remaining ethanol molecules ;
Question
(a) Fig. 9.1 shows two different car tyres.
A car driver observes that her car sinks into soft ground when she uses tyres X. She changes the tyres on her car to Y, so that it does not sink into the soft ground.
Explain why tyre Y will cause less pressure to be exerted on the ground than tyre X.
(b) A thermometer is used to measure the temperature of the air in a tyre.
Fig. 9.2 shows a simple liquid-in-glass thermometer.
(i) State the name of the temperature scale used in the thermometer in Fig. 9.2.
(ii) The liquid in the thermometer is alcohol.
State the physical property of alcohol that varies with temperature used in this thermometer.
(iii) State the two physical properties that define the fixed points on this temperature scale.
1 …………………………………………………………………………
2 …………………………………………………………………………
(c) Fig. 9.3 shows two horizontal forces acting on a car as it moves along a straight road.
(i) Calculate the size and direction of the resultant horizontal force on the car.
size of resultant force = ……………………………………………………………………………….
direction of resultant force …………………………………………………………………………
(ii) The driver of the car applies the brakes to slow the car.
Fig. 9.4 shows the force from the driver’s foot on the brake pedal.
Calculate the moment of the force from the driver’s foot about the pivot.
moment = ………………………………………… Ncm
▶️Answer/Explanation
Ans : 9(a) any one from greater surface area (in contact with ground) ;
same force acts over a larger area ;
9(b)(i) celsius ;
9(b)(ii) volume ;
9(b)(iii) melting point of ice / freezing point of water (0) ;
boiling point of water (100) ;
9(c)(i) 350 (N) ;
to the right / forward ;
9(c)(ii) moment = force × (perpendicular) distance or formula or 40 × 18 ;
= 720 (N cm) ;
Question
A room in a house has an electric heater.
(a) Fig. 12.1 shows part of the circuit containing the heater.
Complete the circuit diagram in Fig. 12.1 by adding the correct electrical symbol for a fuse.
(b) When the circuit is switched on, the current in the heater is 3A and the supply voltage is 240V.
(i) Calculate the resistance of the heater.
State the unit of your answer.
resistance = ……………………………….. unit ………..
(ii) The fuse in the circuit needs to be replaced.
Explain why a 5A fuse is used and not a 3A fuse.
(c) Fig. 12.2 shows the heater as part of an underfloor heating system.
(i) When the heater is switched on, thermal energy passes through the solid floor to heat the air in the room.
The temperature of the air in the room increases slowly.
State the method of thermal energy transfer through the solid floor.
(ii) State the method of thermal energy transfer that heats all the air in the room.
(d) Some water spills onto the floor and evaporates.
Describe evaporation in terms of the motion of water molecules.
(e) There are solar cells on the roof of the house.
State one advantage and one disadvantage of generating electricity using solar cells. Do not include the cost.
advantage ………………………………………………………………………
disadvantage ………………………………………………………………….
▶️Answer/Explanation
Ans : 12(a) fuse inserted in gap using the correct symbol ;
12(b)(i) evidence of resistance = voltage / current (in any form) or 240 / 3 ;
= 80 ;
Ω / ohms ;
12(b)(ii) fuse needs to be slightly greater than maximum current (or it would blow in normal use) ;
12(c)(i) conduction ;
12(c)(ii) convection ;
12(d) faster moving / most energetic molecules (leave) ;
(leave) from the surface of the liquid ;
12(e) renewable energy / does not produce CO2 etc ;
need sunlight / only works during the day etc ;
Question
(a) Water vapour in the air over the sea comes from liquid water in the sea.
(i) State the name of the process by which liquid water in the sea forms water vapour in the air.
…………………………………………………………………………………………………………………….
(ii) Describe how the process named in (i) occurs. Use ideas about water molecules in your answer.
………………………………………………………………………………………………………………………….
………………………………………………………………………………………………………………………….
(b) Fig. 6.1 shows a boat moving at constant speed.
Four forces A, B, C and D act on the boat.
State the name of force C.
…………………………………………………………………………………………………………………….
(c) Fig. 6.2 shows a speed-time graph for the boat.
(i) Determine the speed of the boat.
speed = …………………………………………. m/s
(ii) Calculate the distance travelled by the boat in 200s.
distance = …………………………………………….. m
(d) Fig. 6.3 shows a wave similar to a water wave on the surface of the sea.
(i) Determine the wavelength of the wave.
wavelength = …………………………………………….. m
(ii) On Fig. 6.3, indicate with a double headed arrow (↕ or ↔) the amplitude of the wave.
(iii) The frequency of the wave is 0.08Hz.
Calculate how many wavefronts pass a fixed point in 25 seconds.
▶️Answer/Explanation
Ans: 6(a)(i) evaporation
6(a)(ii) fastest moving/most energetic molecules/particles ;
escape from surface ;
6(b) Weight ;
6(c)(i) 4.4 (m/s) ;
6(c)(ii) distance = speed × time (in any form symbols or words) or 4.4 × 200 or area under graph ;
880 (m) ;
6(d)(i) 8 (m) ;
6(d)(ii) amplitude correctly indicated ;
6(d)(iii) 2.0 ;
Question
(a) An electric heater is used to heat a classroom in a school.
The arrows on Fig. 12.1 show the circulation of air around the classroom.
P and Q are two positions within the air circulation.
Complete the sentences using words from the list.
conduction convection cooled radiation warmed
Position P shows ………………………………. air.
Position Q shows ………………………………. air.
This method of thermal energy transfer is called ………………………………. .
(b) In the classroom, a student draws diagrams to represent the three states of matter.
Fig. 12.2 shows the diagrams drawn. Box X shows the arrangement of particles in a solid.
Box Y shows the arrangement of particles in a liquid.
(i) In box Z, draw the arrangement of particles in a gas.
(ii) Complete the sentences below using only the words solid, liquid and gas.
Solidification occurs when a …………………………….. turns into a …………………………….. .
Condensation occurs when a …………………………….. turns into a …………………………….. .
(iii) State the melting point and the boiling point of water at standard atmospheric pressure.
melting point = ……………….. °C
boiling point = ………………… °C
(c) In another lesson, the student builds an electric circuit.
Fig. 12.3 shows the circuit diagram.
(i) State the name of the components represented by the symbols in Table 12.1.
(ii) When there is a potential difference of 6V across the lamp, a current of 0.3A passes through the lamp.
Calculate the resistance of the lamp.
resistance = …………………………………………….. Ω
▶️Answer/Explanation
Ans: 12(a) cooled ;
warmed ;
convection ;
all correct ;
12(b)(i)
random arrangement and widely spaced ;
12(b)(ii) liquid and
solid ;
gas and
liquid ;
12(b)(iii) 0 °C and 100 °C ;
12(c)(i) ammeter ;
voltmeter ;
12(c)(ii) R = V ÷ I (symbols or words) or 6 ÷ 0.3 ;
R = 20 (Ω) ;
Question
An astronomer observes a large meteorite, a rock from outer space. The astronomer uses a telescope which contains mirrors.
Fig. 12.1 shows the image of the meteorite seen in the mirror by the astronomer.
(a) Select two words or phrases from the list to describe the characteristics of an image formed by a single plane mirror.
▶️Answer/Explanation
The two characteristics of an image formed by a single plane mirror are:
- same size
- upright
(b) The meteorite enters the Earth’s atmosphere.
Fig. 12.2 is a speed-time graph for the meteorite as it approaches Earth.
(i) On Fig. 12.2, label with an S a point when the meteorite is slowing down.
▶️Answer/Explanation
The meteorite slows down when it experiences air resistance, which occurs after it reaches its maximum speed. Label a point on the graph where the speed starts to decrease.
S somewhere between 5 s and 12 s
(ii) State the form of energy lost by the meteorite as it slows down.
▶️Answer/Explanation
The meteorite loses kinetic energy as it slows down due to air resistance and friction with the atmosphere.
(iii) Use Fig. 12.2 to determine the maximum speed of the meteorite.
▶️Answer/Explanation
The maximum speed of the meteorite is 36,000 m/s, as indicated by the highest point on the speed-time graph.
(c) The mass of the meteorite is 22,500 kg. The density of the meteorite is 7500 kg/m3.
(i) Calculate the volume of the meteorite.
▶️Answer/Explanation
Using the formula: Volume = Mass ÷ Density,
Volume = 22,500 kg ÷ 7500 kg/m3 = 3.0 m3.
(ii) A scientist suggests that the meteorite contains metallic iron.
Suggest a simple way for the scientist to test for iron in an object found on Earth.
▶️Answer/Explanation
The scientist can use a magnet to test for the presence of iron. If the object is attracted to the magnet, it likely contains iron.
(d) The meteorite’s temperature is 1500°C when it falls into the sea. The meteorite loses thermal energy to the water.
(i) State the main method of thermal energy transfer from the meteorite into the water.
▶️Answer/Explanation
The main method of thermal energy transfer from the meteorite into the water is conduction, as the heat is transferred through direct contact between the meteorite and the water.
(ii) Some of the seawater evaporates.
Describe the process of evaporation in terms of the movement and energy of water molecules.
▶️Answer/Explanation
Evaporation occurs when the most energetic water molecules at the surface gain enough energy to escape into the air as gas. This process cools the remaining liquid as the higher-energy molecules leave.
(iii) The meteorite is a solid and the seawater is a liquid.
Draw more circles in the boxes in Fig. 12.3 to show the arrangement and separation of particles in a solid and in a liquid.
▶️Answer/Explanation
In a solid, particles are closely packed in a regular arrangement. In a liquid, particles are close together but not in a fixed arrangement, allowing them to move past each other.
Question
Fig. 9.1 shows a tumble dryer.
In a tumble dryer, wet clothes are warmed and dried. Water on the clothes evaporates.
(a) (i) Describe the process of evaporation. Use ideas about molecules in your answer.
▶️Answer/Explanation
Evaporation is the process by which molecules at the surface of a liquid gain enough energy to escape into the gas phase. In the case of water, faster-moving or more energetic molecules at the surface can overcome the intermolecular forces holding them in the liquid and escape as water vapour. This process occurs even below the boiling point of the liquid.
(ii) During evaporation, the water does not boil. State the boiling point of water.
▶️Answer/Explanation
The boiling point of water is 100°C at standard atmospheric pressure.
(iii) Inside the tumble dryer, water vapour changes into liquid water. State the term used to describe a gas changing into a liquid.
▶️Answer/Explanation
The term used to describe a gas changing into a liquid is condensation.
(iv) Thermal energy passes through the metal casing of the tumble dryer. State the method of thermal energy transfer through metals.
▶️Answer/Explanation
The method of thermal energy transfer through metals is conduction.
(b) The tumble dryer is noisy and emits loud sound waves with a low pitch.
(i) Describe the sound waves in terms of their amplitude and frequency.
▶️Answer/Explanation
Loud sound waves have a large amplitude, which corresponds to the volume or loudness of the sound. A low pitch indicates that the sound waves have a low frequency, meaning fewer wave cycles per second.
(ii) State the lowest audible frequency for a healthy human ear. State the unit of your answer.
▶️Answer/Explanation
The lowest audible frequency for a healthy human ear is 20 Hz (Hertz).
(iii) The speed of sound in air is 340 m/s. Calculate the time taken for a sound wave to travel 85 m.
▶️Answer/Explanation
To calculate the time taken for a sound wave to travel 85 m, we use the formula:
\[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} = \frac{85 \, \text{m}}{340 \, \text{m/s}} = 0.25 \, \text{s} \]
Therefore, the time taken is 0.25 seconds.