Q1.
Americium-241 is an isotope of americium.
(a) Which of the isotopes given in the table below is not an isotope of americium?
Isotope Mass number Atomic number
A 243 95
B 243 94
C 242 95
Isotope B
Give a reason for your answer.
Isotopes are the same elements with the same number of neutrons but a different
number of protons. Isotope B, like americium, is supposed to have 148 neutrons and
95 protons to add up to 243. Yet isotope B does not contain 148 neutrons, but 149,
with 94 protons that makes it add up to a mass number of 242.
(2)
The graph below shows how the number of americium-241 nuclei in a sample changes
with time.
(b) How many years does it take for the number of americium-241 nuclei to decrease
from 10 000 to 5000?
Time = 440 years
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(1)
(c) What is the half-life of americium-241?
Half-life = 440 years
(1)
(Total 4 marks)
Q2.
Atoms contain three types of particle.
(a) Draw a ring around the correct answer to complete the sentence.
electrons and neutrons.
The particles in the nucleus of the atom are electrons and protons.
neutrons and protons.
(1)
(b) Complete the table to show the relative charges of the atomic particles.
Particle Relative charge
Electron –1
Neutron 0
Proton +1
(2)
(c) (i) A neutral atom has no overall charge.
Explain this in terms of its particles.
In a neutral atom,
(2)
(ii) Complete the sentence.
An atom that loses an electron is called an ion and has an overall positive
charge.
(2)
(Total 7 marks)
Q3.
Alpha, beta, and gamma are types of nuclear radiation.
(a) Draw one line from each type of radiation to what the radiation consists of.
Type of radiation What radiation consists of
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Electron from the nucleus
Alpha
Two protons and two neutrons
Beta
Electromagnetic radiation
Gamma
Neutron from the nucleus
(3)
(b) A teacher demonstrates the penetration of alpha, beta and gamma radiation through
different materials.
The demonstration is shown in the figure below.
Gamma
Beta
Alpha
Complete the figure above by writing the name of the correct radiation in each box.
(2)
(c) Give two safety precautions the teacher should have taken in the demonstration.
1. Protective clothing with badge to ensure the amount of radiation exposed.
2. Contain the radiation and radioactive material in a safe place away from people.
(2)
(d) The table below shows how the count rate from a radioactive source changes with
time.
Time in seconds 0 40 80 120 160
Count rate
400 283 200 141 100
in counts/second
Use the table to calculate the count rate after 200 seconds.
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72 *used graph*
(2)
(e) The half-life of the radioactive source used was very short.
Give one reason why this radioactive source would be much less hazardous after
800 seconds.
The half life of this source is 80 seconds, so after 800 seconds, this source would
have completed 10 half-lives, making it less hazardous.
(1)
(Total 10 marks)
Q4.
Alpha particles, beta particles and gamma rays are types of nuclear radiation.
(a) Describe the structure of an alpha particle.
A highly ionising particle containing 2 protons and 2 neutrons-much identical to a
helium particle.
(1)
(b) Nuclear radiation can change atoms into ions by the process of ionisation.
(i) Which type of nuclear radiation is the least ionising?
Tick (✔) one box.
alpha particles
beta particles
gamma rays
(1)
(ii) What happens to the structure of an atom when the atom is ionised?
It loses its electrons. If it is singly ionised, it loses its outermost electron.
(1)
(c) People working with sources of nuclear radiation risk damaging their health.
State one precaution these people should take to reduce the risk to their health.
Wear protective clothing with a TLD badge (a badge with a similar role as a film
badge dosimeter) to keep track of the radiation the workers are exposed to.
(1)
(Total 4 marks)
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