Practise Edexcel A-Level Physics nuclear decay through binding energy, fusion and fission, radiation properties, nuclear equations and radioactive half-life calculations.
A nucleus of polonium-210 decays to lead-206 by emitting an alpha particle. The masses of the particles are shown in the table.
Show that the energy released in the decay is about .
Actinium-225 is a radioactive isotope. It decays to francium by emitting alpha particles. Actinium-225 has a short half-life, which makes it suitable for medical applications.
Complete the nuclear equation for this decay.
In a radioactive decay, energy is released and the total mass decreases.
Show that the energy released if the mass decreases by 1 u is about 930 MeV .
The activity of a sample of actinium-225 is 7.4 × 10^7 Bq when it is prepared.
Calculate the number of actinium atoms in the sample 7.0 days later.
half-life of actinium-225 = 9.9 days
Number of actinium atoms after 7.0 days =
In France, scientists from many countries are working together to build the International Thermonuclear Experimental Reactor (ITER).
On the ITER website it states:
"Fusion is the energy source of the Sun and stars. In the core of these stellar bodies, hydrogen nuclei fuse into helium nuclei and release tremendous amounts of energy."
Explain why energy is released when hydrogen nuclei fuse to form helium nuclei.
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It is hoped that the ITER will be the first fusion device on Earth to maintain nuclear fusion for long periods of time.
To achieve fusion in the ITER, a hot plasma is used.
The plasma must
- be at an extremely high temperature
- have sufficient density for fusion.
Explain why each of these two conditions must be met.
The graph shows the variation of binding energy per nucleon with proton number Z.
In one possible fusion reaction, a nucleus of ²H fuses with a nucleus of ³H to form a nucleus of ⁴He and a neutron.
Calculate the energy released in this reaction.
Actinium-225 is a radioactive isotope. It decays to francium by emitting alpha particles. Actinium-225 has a short half-life, which makes it suitable for medical applications.
In a radioactive decay, energy is released and the total mass decreases.
Show that the energy released if the mass decreases by 1 u is about 930 MeV .
In France, scientists from many countries are working together to build the International Thermonuclear Experimental Reactor (ITER).
It is hoped that the ITER will be the first fusion device on Earth to maintain nuclear fusion for long periods of time.
To achieve fusion in the ITER, a hot plasma is used.
The plasma must
- be at an extremely high temperature
- have sufficient density for fusion.
Explain why each of these two conditions must be met.
A student used a detector and counter to measure the background radiation count for five minutes. He used this value to calculate the background count rate.
Which of the following would increase the accuracy of the student's value for the background count rate?
Decrease the counting time to 1 minute.
Increase the counting time to 10 minutes.
Repeat the count with a different detector and calculate a mean value.
Repeat the count in a different location and calculate a mean value.
A student investigated the absorption of gamma radiation by lead, as shown. She used an americium source.
She placed sheets of lead absorber between the source and the GM tube. She recorded the count for 2 minutes for each thickness of absorber.
Americium emits alpha radiation as well as gamma radiation.
State why alpha radiation will not affect the recorded count rate.
Actinium-225 is a radioactive isotope. It decays to francium by emitting alpha particles. Actinium-225 has a short half-life, which makes it suitable for medical applications.
Complete the nuclear equation for this decay.
A student investigated the absorption of gamma radiation by lead, as shown. She used an americium source.
She placed sheets of lead absorber between the source and the GM tube. She recorded the count for 2 minutes for each thickness of absorber.
The student plotted a graph of count rate R against thickness x of absorber. Her graph is shown below.
R varies with x according to the equation
where is a constant.
Determine a value for .
Which of the following correctly describes the random nature of radioactive decay?
Radioactive decay is a natural process.
Radioactive decay is a spontaneous process.
We cannot influence when a decay will take place.
We cannot predict when a decay will take place.
Actinium-225 is a radioactive isotope. It decays to francium by emitting alpha particles. Actinium-225 has a short half-life, which makes it suitable for medical applications.
The activity of a sample of actinium-225 is 7.4 × 10^7 Bq when it is prepared.
Calculate the number of actinium atoms in the sample 7.0 days later.
half-life of actinium-225 = 9.9 days
Number of actinium atoms after 7.0 days =