WorksheetsIGCSE Topic 7 Radioactivity
Total questions: 25
Worksheet time: 25mins
Which line in the table describes the nature of an alpha-particle and a gamma-ray?
A
B
C
D
A radioactive nucleus R decays with the emission of a β-particle as shown:
Which equation is correct?
x = p
y = q
p = x – 1
q = y – 1
The equation shows the decay of the nuclide X:
What are the values of P and Q ?
A
B
C
D
Which type of radiation has the greatest ionising effect?
α-particles
β-particles
γ-rays
all have the same ionising effect
Which particles are found in the nucleus of an atom?
neutrons and protons only
neutrons only
protons and electrons only
protons, electrons and neutrons
A Geiger counter detects radiation from radioactive sources.
A radioactive source is inside a thick aluminium container as shown:
Which type of radiation from this source is being detected?
α-particles
β-particles
γ-rays
radio waves
A radioactive isotope has a half-life of 2 minutes. What can be deduced from this statement?
After 2 minutes, half of the isotope remains.
After 1 minute, half of the isotope remains.
After 4 minutes, half of the isotope remains.
After 4 minutes, none of the isotope remains.
A detector is used to measure the count-rate near a radioactive source. The reading is 4000
counts per minute. After 30 minutes the count-rate has fallen to 500 counts per minute.
What is the half-life of the radioactive source? You may ignore the effects of background
radiation.
3 minutes
5 minutes
6 minutes
10 minutes
The half-life of a radioisotope is 2400 years. The activity of a sample is 720 counts /s.
How long will it take for the activity to fall to 90 counts /s?
300 years
2400 years
7200 years
19 200 years
What occurs in the decay of a radioactive nucleus?
The nucleus absorbs another nucleus.
The nucleus absorbs at least one form of radiation.
The nucleus always splits into two equal fragments.
The nucleus emits at least one form of radiation.
A student investigates a radioactive source that emits only alpha-particles. Without any source
nearby, the detector shows a low reading. The source and thick cardboard are placed near the detector, as shown:
What is the reading on the detector now, and why?
A
B
C
D
In nuclear ……1……, hydrogen nuclei ……2…… to form helium nuclei, releasing energy.
Which words correctly complete gaps 1 and 2?
A
B
C
D
Ra decays with a half-life of 1600 s.
Rn decays with a half-life of 52 s.
Po decays with a half-life of 9.1 s.
Pb decays with a half-life of 10.6 h.
The changing count rate for one of these radioactive nuclides is shown in the graph.
From the half-life shown by the graph, which was the decaying radioactive nuclide?
Ra
Rn
Po
Pb
How many nucleons are in a nucleus of ?
19
20
39
58
Compared with β-particles and γ-rays, α-particles
are the only type of radiation to carry a charge.
have the greatest ionising effect.
have the greatest penetrating effect.
have the smallest mass.
The diagram shows a box used for storing radioactive sources.
Which material is best for lining the box to prevent the escape of most radioactive emissions?
aluminium
copper
lead
steel
The count rate from a radioactive isotope is recorded every hour. The count rate is corrected forbackground radiation.
The table shows the readings.
What estimate of the half-life of the isotope can be obtained from the readings in the table?
between 1 and 2 hours
between 2 and 3 hours
between 3 and 4 hours
between 4 and 5 hours
The half-life of a radioactive substance is 10 minutes. A sample of the radioactive substancecontains 2000 nuclei.
How many radioactive nuclei were in the sample half an hour earlier?
250
4000
6000
16 000
A radiation detector is placed close to a source of β-particles.
Aluminium sheets of increasing thickness are placed between the source and the detector.
Eventually a sheet which is 2.0 cm thick is used. The reading on the detector decreases, but does not fall to zero.
Why does the reading not fall to zero?
Some of the β-particles go round the edges of the sheet.
The detector is too close to the source.
There is always some background radiation.
The sheet can never be thick enough to absorb all the β-particles
A radioactive nucleus emits a β-particle.
What happens to the proton number (atomic number) of the nucleus?
It stays the same.
It increases by 1.
It decreases by 2.
It decreases by 4.
A scientist needs to use a source of γ-rays as safely as possible.
Which action will not reduce the amount of radiation that reaches the scientist?
keeping the distance between the source and the scientist as large as possible
keeping the temperature of the source as low as possible
keeping the time for which the scientist uses the source as small as possible
placing a lead screen between the scientist and the source
The arrangement shown is used to check whether the flour inside a cardboard packet is above a certain level. If it is above this level, the flour absorbs the radiation from the source so that it doesn’t reach the detector.
Which type of radiation is suitable to use?
α-particles only
β-particles only
either α-particles or β-particles
γ-rays only
Which of these is a use of alpha radiation?
Sterilising food
Smoke detectors
Monitoring paper thickness
Industrial tracers
