Nuclear PhysicsOxford AQA IGCSE Physics: Topic test

20 questions, 54 marks

Oxford AQA IGCSE Physics

Nuclear Physics topic test

Total 54 marks

Name

Class

Date

1
A water-testing laboratory uses a mass spectrometer to separate two naturally occurring isotopes of chlorine found in a water sample: chlorine-35 and chlorine-37. Both isotopes have an atomic (proton) number of 17.
(a)
What is different between the two isotopes of chlorine?
[1 mark]
AThe number of protons
BThe number of neutrons
CThe number of electrons in a neutral atom
DThe overall charge of a neutral atom
(b)
Which of the following correctly states the relative charge of a neutron?
[1 mark]
A+1
B-1
C0
D+2
(c)
Calculate the number of neutrons in a neutral atom of chlorine-37, and state the number of electrons it contains.
[2 marks]
Total for question 1: 4 marks
2
A laboratory technician tests three unlabelled sealed radioactive sources using a Geiger-Muller tube connected to a counter. For source X, a single sheet of paper reduces the count rate to background level. For source Y, only a thick lead block reduces the count rate to background level; paper and a few millimetres of aluminium have no effect. For source Z, a few millimetres of aluminium reduces the count rate to background level, but paper alone does not.
(a)
Based on this, which type of radiation is source X most likely emitting?
[1 mark]
AAlpha
BBeta
CGamma
DX-rays
(b)
Based on this, which type of radiation is source Y most likely emitting?
[1 mark]
AAlpha
BGamma
CBeta
DBackground radiation only, no source present
(c)
Identify the type of radiation emitted by source Z, and explain your reasoning in terms of penetrating power.
[2 marks]
Total for question 2: 4 marks
3
A physics textbook describes a single fission event: a slow-moving neutron is absorbed by a uranium-235 nucleus, which becomes unstable and splits into two smaller nuclei, releasing 3 neutrons and a large amount of energy. In a hypothetical uncontrolled sample containing many uranium-235 nuclei, each released neutron goes on to be absorbed by another uranium-235 nucleus, causing further fission events.
(a)
Explain the process of nuclear fission that occurs when the uranium-235 nucleus absorbs the neutron, including what happens to the products and the energy released.
[3 marks]
(b)
Explain why, in this hypothetical uncontrolled sample, the number of fission events happening each moment would rapidly increase, and describe, in terms of neutrons, the one condition that must be met inside a working nuclear reactor's core to keep a chain reaction steady rather than increasing uncontrollably.
[4 marks]
Total for question 3: 7 marks
4
A factory uses a sealed cobalt-60 source to sterilise batches of medical bandages by gamma irradiation. The source is kept inside a thick lead-lined chamber, and staff working nearby wear radiation dosimeter badges. Cobalt-60 has a half-life of about 5.3 years, so the source's activity gradually decreases and must eventually be replaced.
(a)
Cobalt-60 can be represented using the notation $^{60}_{27}\text{Co}$ . Explain what the numbers 60 and 27 represent, state how many protons, neutrons and electrons a neutral atom of cobalt-60 contains, and explain what is meant by describing cobalt-60 as an isotope of cobalt.
[6 marks]
(b)
Explain why gamma radiation, rather than alpha or beta, is the most suitable type for sterilising bandages inside a sealed source, and explain, using ideas about half-life, why the factory will eventually need to replace the cobalt-60 source even though it is not being used up chemically.
[6 marks]
Total for question 4: 12 marks
5
A physics teacher demonstrates ion formation to a class, explaining that a neutral sodium atom, represented using the notation $^{23}_{11}\text{Na}$ , can lose one electron to form a sodium ion, $\text{Na}^+$ .
(a)
How many protons does a neutral sodium atom, $^{23}_{11}\text{Na}$ , contain?
[1 mark]
A23
B12
C34
D11
(b)
The sodium atom loses one electron to form the ion $\text{Na}^+$ . What is the overall charge of this ion?
[1 mark]
A0
B-1
C+2
D+1
(c)
State the number of neutrons in this sodium atom, and explain why the sodium ion has a different number of electrons from protons.
[2 marks]
Total for question 5: 4 marks
6
A water company adds a small amount of a gamma-emitting radioactive tracer to water flowing through an underground pipe network, then uses a detector moved along the ground above the pipes to find a suspected leak by looking for higher count rates escaping into the surrounding soil.
(a)
Which type of radiation is most suitable for this tracer technique, given it must pass through the pipe wall and surrounding soil to reach a detector above ground?
[1 mark]
AAlpha, because it is the most ionising
BBeta, because it has a short range
CGamma, because it is the most penetrating
DNone of these, as no radiation can pass through soil
(b)
Which of the following is a natural source of background radiation, separate from the tracer added by the water company?
[1 mark]
ACosmic rays from space
BThe gamma-emitting tracer itself
CThe detector used to find the leak
DThe underground pipe network
(c)
State one reason gamma radiation is more suitable than alpha radiation for this tracer technique, and state one radiation safety precaution the workers should take.
[2 marks]
Total for question 6: 4 marks
7
A science teacher demonstrates nuclear fusion to a class using an analogy: two strong magnets are pushed together with their north poles facing each other to represent the repulsion between two positive hydrogen nuclei, showing that a large push (representing very high temperature and pressure) is needed to force them close enough together to fuse.
(a)
Explain, using ideas about electrostatic repulsion, why very high temperatures and pressures are needed to force two hydrogen nuclei close enough together to fuse.
[3 marks]
(b)
Define nuclear fusion, state what happens to the total mass of the nuclei during fusion, and explain what this implies about the energy released.
[4 marks]
Total for question 7: 7 marks
8
A physics textbook compares two nuclear reactions: the fission of a single uranium-235 nucleus, which releases about $3.2 \times 10^{-11}$ J of energy, and the fusion of two hydrogen nuclei to form a helium nucleus, which releases about $4.0 \times 10^{-12}$ J of energy. Both values are far larger than the energy released by a single chemical reaction, such as the combustion of one methane molecule, which releases around $10^{-18}$ J.
(a)
Explain the process of nuclear fission that releases the $3.2 \times 10^{-11}$ J from the uranium-235 nucleus, and explain why this energy release is so much larger than that of the chemical combustion reaction.
[6 marks]
(b)
Explain the process of nuclear fusion that releases the $4.0 \times 10^{-12}$ J of energy when two hydrogen nuclei join to form a helium nucleus, referring to the need to overcome electrostatic repulsion, and explain why more energy is released per event by the fission reaction than by this fusion reaction, even though both are nuclear reactions.
[6 marks]
Total for question 8: 12 marks

End of questions