Atomic Physics and RadioactivityIB MYP Physics: Topic test

20 questions, 54 marks

IB MYP Physics

Atomic Physics and Radioactivity topic test

Total 54 marks

Name

Class

Date

1
Chlorine has two common isotopes, chlorine-35 and chlorine-37. Atoms of both have atomic number 17. A student in Doha is making bead models of the two atoms for a class display.
(a)
How many neutrons are in a chlorine-37 atom?
[1 mark]
A17
B18
C20
D37
(b)
Which particle has a relative mass of about $\frac{1}{1840}$ and is found in the shells of an atom?
[1 mark]
AElectron
BProton
CNeutron
DAlpha particle
(c)
Explain why chlorine-35 and chlorine-37 are isotopes of the same element.
[2 marks]
Total for question 1: 4 marks
2
A laboratory in Seoul studies two unstable nuclei. Radium-226 has atomic number 88 and decays by emitting an alpha particle. Strontium-90 has atomic number 38 and decays by emitting a beta particle.
(a)
What is the mass number of the nucleus formed when radium-226 emits an alpha particle?
[1 mark]
A230
B222
C226
D224
(b)
What is the atomic number of the nucleus formed when strontium-90 emits a beta particle?
[1 mark]
A37
B38
C89
D39
(c)
State which of the two types of radiation, alpha or beta, is stopped by a sheet of paper, and name a material that is needed to stop the other.
[2 marks]
Total for question 2: 4 marks
3
A clinic in Mumbai treats an overactive thyroid gland with iodine-131, which has a half-life of 8 days. A delivery of iodine-131 arrives with an activity of 640 MBq.
(a)
Calculate the activity of the delivery 24 days after it arrived.
[3 marks]
(b)
Explain why an isotope with a half-life of 5 minutes, or one with a half-life of 5000 years, would be less suitable than iodine-131 for this treatment.
[4 marks]
Total for question 3: 7 marks
4
A water company in Jakarta wants to find a leak in a buried pipe without digging up the road. It injects a small amount of a radioactive tracer that emits gamma rays into the water and uses a Geiger-Muller tube above ground to find where the tracer escapes. A technician measures the corrected count rate from a sample of the tracer: 1600 counts per second at the start, 800 counts per second after 6 hours and 400 counts per second after 12 hours. The alternative is to dig up the pipe along its whole length.
(a)
Determine the half-life of the tracer and predict its corrected count rate after 24 hours. Explain why a gamma emitter with a short half-life is a sensible choice of tracer.
[6 marks]
(b)
Discuss whether the company should use the radioactive tracer rather than digging up the pipe along its whole length.
[6 marks]
Total for question 4: 12 marks
5
Stars such as the Sun release energy by nuclear fusion. In the core of the Sun, hydrogen nuclei join together to make helium nuclei at a temperature of about 15 million °C and at very high pressure.
(a)
What happens during nuclear fusion?
[1 mark]
AA large nucleus splits into two smaller nuclei after absorbing a neutron
BAn unstable nucleus emits an alpha particle and becomes a different element
CAn unstable nucleus emits gamma rays and keeps the same numbers of protons and neutrons
DTwo small nuclei join to form a larger nucleus and energy is released
(b)
Which is a main challenge in building a fusion power station on Earth?
[1 mark]
AHydrogen fuel is extremely scarce
BReaching and containing a temperature of millions of degrees
CThe fuel has to be mined as uranium-235
DThe reaction makes large amounts of very long-lived radioactive waste
(c)
Explain why a very high temperature is needed for hydrogen nuclei to fuse.
[2 marks]
Total for question 5: 4 marks
6
A museum in Toronto has an exhibit on how the model of the atom changed. Dalton (1803) pictured atoms as tiny solid spheres. Thomson (1897) pictured a ball of positive charge with negative electrons embedded in it. Rutherford (1911) placed a tiny, dense, positively charged nucleus at the centre. Bohr (1913) placed the electrons in fixed shells around the nucleus.
(a)
Which scientist first described electrons in fixed shells around the nucleus?
[1 mark]
ABohr
BDalton
CThomson
DRutherford
(b)
Which statement describes the atom in Thomson's model?
[1 mark]
AA solid sphere with no smaller parts inside it
BA tiny dense nucleus surrounded by mostly empty space
CA ball of positive charge with negative electrons embedded in it
DA nucleus with electrons moving in fixed shells
(c)
State two differences between Thomson's model and Rutherford's model of the atom.
[2 marks]
Total for question 6: 4 marks
7
A student in Dubai uses a Geiger-Muller tube to identify the radiation from a sealed source that emits only one type of radiation. Before the source is brought near, the tube records 90 counts in 3 minutes. With the source close to the tube, the raw count rate is 550 counts per minute with nothing in between. It is 548 counts per minute with a sheet of paper in between, 62 counts per minute with 3 mm of aluminium in between, and 31 counts per minute with 2 cm of lead in between.
(a)
Calculate the background count rate in counts per minute, and the corrected count rate from the source with nothing in between.
[3 marks]
(b)
Identify the type of radiation emitted and use the data to justify your answer.
[4 marks]
Total for question 7: 7 marks
8
A school in Lagos has been offered a sealed gamma source and a Geiger-Muller tube for practical lessons. The students want to investigate how the count rate changes as the tube is moved further away from the source. The school's governors must decide whether schools should be allowed to keep sealed radioactive sources at all.
(a)
Design an investigation to test how the distance from the source affects the count rate. Include a hypothesis with a reason, the variables, and a safe method.
[6 marks]
(b)
Discuss whether schools should be allowed to keep sealed radioactive sources for practical lessons.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).