CIE iGCSE Co-Ordinated Science P5.2.2 The three types of nuclear emission Exam Style Questions Paper 3
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) Doctors use ionising and non‐ionising radiations in hospitals.
(i) Table 3.1 lists some radiations.
Put a tick (✓) in each row of Table 3.1 to show which radiations are ionising and a cross (✗) to show which radiations are not ionising.
Two have been done for you.
(ii) Describe one adverse effect of ionising radiations on living things.
………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………….
(iii) Place alpha (α), beta (β) and gamma (γ) radiations in order of their relative penetrating ability.
most penetrating ……………………………….
……………………………….
least penetrating ……………………………….
(iv) State one use of X‐rays in a hospital.
………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………….
(v) Ultrasound waves are used to scan unborn babies.
Ultrasound waves have a frequency above the maximum audible frequency for a human.
Suggest a frequency for ultrasound waves.
State the unit of your answer.
frequency = …………………………………………….. unit …………..
(b) (i) Gamma (γ) radiation is used in hospitals to destroy cancer cells.
Fig. 3.1 shows an incomplete electromagnetic spectrum.
Write gamma (γ) radiation in its correct place.
(ii) State the region of the electromagnetic spectrum where the waves have the lowest frequency.
…………………………………………………………………………………………………………………….
(c) A radioactive isotope of iodine, iodine‐123, is used by a doctor to examine the thyroid gland of a patient.
The nuclide notation for the isotope is $_{53}^{123}\textrm{I}$
State what the numbers 123 and 53 represent.
123 …………………………………………………………………………………………………………………………..
53 …………………………………………………………………………………………………………………………….
▶️Answer/Explanation
Ans: 3(a)(i)
2 correct ;
3 correct ;
3(a)(ii) cancer / mutation ;
3(a)(iii) gamma
beta
alpha ;
3(a)(iv) to view internal body structures ;
3(a)(v) any value higher than 20 000 ;
Hz ;
3(b)(i) $\gamma $–radiation in left hand box ;
3(b)(ii) radio waves ;
3(c) 123 is nucleon number ;
53 is proton number ;
Question
(a) (i) Complete the sentences to describe the energy changes that occur during the generation of electricity in a nuclear power station.
Nuclear fission releases ………………………………………… energy which heats up water in a boiler.
When the turbine and generator are turning, they have ………………………………………… energy.
The generator produces ………………………………………… energy.
(ii) Nuclear fission occurs in the nuclear power station.
State what happens to the nucleus of an atom during nuclear fission.
(b) The radioactive decay of plutonium-239 produces an isotope of uranium, uranium-235.
plutonium-239 → uranium-235 + α-particle
(i) State the charge on an α-particle.
(ii) Describe how the numbers of protons and neutrons change in the nucleus of a plutonium-239 atom when it emits an α-particle.
protons …………………………………………………………………………
neutrons …………………………………………………………………………
(iii) The half-life of plutonium-239 is 24 000 years.
A sample of nuclear fuel contains 6.0 g of plutonium-239.
Calculate the mass of plutonium-239 remaining after 72 000 years.
mass = ……………………………………………… g
▶️Answer/Explanation
Ans : 6(a)(i) thermal ;
kinetic ;
electrical ;
6(a)(ii) splits ;
6(b)(i) (2) positive ;
6(b)(ii) protons decrease by 2 or down to 92 ;
neutrons decrease by 2 or down to 143 ;
6(b)(iii) 3 half lives ;
6.0 divided by 2 three times ;
0.75 (g) ;
Question
(a) A spacecraft carrying an astronaut travels 384 000 km from the Earth to the Moon in 78 hours.
Calculate the average speed of the spacecraft in km / s.
average speed = ………………………………………… km / s
(b) The mass of the astronaut on the Earth is 90 kg.
(i) Calculate the weight of the astronaut on the Earth.
The gravitational force on unit mass, g, is 10 N / kg.
weight = …………………………………………….. N
(ii) State the mass of the astronaut on the Moon.
mass = ……………………………………………. kg
(c) (i) The astronaut communicates with Earth using radio waves.
Fig. 3.1 shows an incomplete electromagnetic spectrum.
Write radio waves in the correct position in Fig. 3.1.
(ii) Explain why it is not possible for the astronaut to communicate with Earth using sound waves.
(d) The astronaut collects a lump of moon rock.
The rock contains iron-60, a radioactive isotope.
(i) State the meaning of the term isotope.
(ii) Iron-60 decays by the emission of β-particles.
Complete the sentences to describe the nature of β-particles.
β-particles are identical in nature to ………………………………… .
β-particles have a single ………………………………… charge.
▶️Answer/Explanation
Ans : 3(a) 78 hours = 78 × 3600 = 280 800 seconds ;
speed = distance / time (in any form) or 384 000 / 280 800 ;
= 1.37 (km / s) ;
3(b)(i) weight = mass × g (in any form) or 90 × 10 ;
= 900 (N) ;
3(b)(ii) 90 (kg) ;
3(c)(i) radio (waves) in right hand box ;
3(c)(ii) sound waves need a medium / sound waves do not travel through a vacuum ;
3(d)(i) atoms of the same element that have different numbers of neutrons ;
OR
atoms which have the same number of protons and different numbers of neutrons ;
OR
atoms which have the same atomic number but different mass number ;
3(d)(ii) electrons ;
negative ;
Question
(a) Thermal energy is released, by combustion, in a gas-fired power station.
Describe how the thermal energy released is transferred into electrical energy in the power station.
…………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………
(b) State one advantage and one disadvantage of a nuclear power station compared with a gas-fired power station.
advantage …………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………
disadvantage …………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………
(c) Cobalt-60 is produced in a nuclear power station.
(i) A sample of cobalt-60 has a mass of 2g.
The half-life of cobalt-60 is 5.25 years.
Calculate the mass of cobalt-60 remaining after 21 years.
mass = ……………………………………………… g
(ii) Cobalt-60 decays by emitting β-particles and γ-rays.
State the charge on a β-particle.
charge = ………………………………………………….
(iii) Place α-particles, β-particles and γ-rays in order of their penetrating abilities.
(iv) Suggest a safe way of storing a small sample of cobalt-60.
………………………………………………………………………………………………………………………….
………………………………………………………………………………………………………………………….
▶️Answer/Explanation
Ans: 3(a) thermal energy turns water to steam ;
steam drives turbine ;
turbine drives generator ;
3(b) advantage – nuclear not reliant on fossil fuels / no CO$_{2}$ produced ;
disadvantage – nuclear accidents / disposal of nuclear waste ;
3(c)(i) 4 half-lives ;
0.125 (g) ;
3(c)(ii) –1 ;
3(c)(iii) most penetrating
$\gamma$
β
$\alpha$
least penetrating ;
3(c)(iv) in a lead lined container ;
Question
(a) Describe how to show that a radioactive isotope is releasing γ-rays but not α-particles or β-particles.
▶️Answer/Explanation
To show that a radioactive isotope is releasing γ-rays but not α-particles or β-particles, you can use a detector that is sensitive to γ-rays, such as a Geiger-Müller tube or a scintillation counter. Place the radioactive source near the detector and observe the readings. Since γ-rays are highly penetrating, they will be detected even if the source is shielded by materials like lead or thick concrete, which would block α and β particles. If the detector still registers radiation through such shielding, it indicates the presence of γ-rays. Additionally, α and β particles can be blocked by thin materials like paper or aluminum, so if the radiation is not blocked by these materials, it further confirms the presence of γ-rays.
(b) In a nuclear reactor, the fission of uranium-235 takes place.
(i) Describe what happens to the nucleus of a uranium-235 atom during nuclear fission.
▶️Answer/Explanation
During nuclear fission, the nucleus of a uranium-235 atom absorbs a neutron, becoming unstable and splitting into two smaller nuclei (fission fragments), along with the release of additional neutrons and a large amount of energy in the form of kinetic energy and γ-rays.
(ii) The half-life of uranium-235 is 704 million years. A sample of uranium-235 has a mass of 0.1 g. Calculate how many grams of uranium-235 will remain in the sample after 704 million years.
▶️Answer/Explanation
After one half-life (704 million years), half of the original sample will have decayed. Therefore, the remaining mass of uranium-235 will be: \[ \text{Remaining mass} = \frac{0.1\, \text{g}}{2} = 0.05\, \text{g} \]
(iii) Uranium-235 and uranium-238 are two isotopes of uranium. Explain what is meant by isotope.
▶️Answer/Explanation
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means they have the same atomic number but different mass numbers. For example, uranium-235 and uranium-238 both have 92 protons, but uranium-235 has 143 neutrons, while uranium-238 has 146 neutrons.
(c) A nuclear power station generates electricity. One use of electricity is to power an electric motor. In a d.c. electric motor, a current-carrying coil in a magnetic field experiences a turning effect. State two factors that can be changed to increase the turning effect in a d.c. motor.
▶️Answer/Explanation
Two factors that can be changed to increase the turning effect in a d.c. motor are:
- Increase the current: A higher current in the coil will increase the magnetic force acting on the coil, resulting in a greater turning effect.
- Increase the strength of the magnetic field: A stronger magnetic field will also increase the force on the coil, leading to a greater turning effect.