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IGCSE Physics: Nuclear physics — Practice Questions & Answers
The atomic nucleus, isotopes, the three radiations, decay equations, half-life, safety, uses, and fission versus fusion.
864 practice questions available for this topic — here are 10 with full answers and explanations.
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Practice questions with answers
1
Multiple choice · Easy
In the nuclear model of the atom, where is almost all of the mass concentrated?
In the nucleus
In the orbiting electrons
Spread evenly throughout the atom
In the empty space around the nucleus
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Why Protons and neutrons (nucleons) make up nearly all the atom's mass and are located in the tiny central nucleus; electrons are very light.
2
Multiple choice · Easy
What is the proton number (atomic number) of an atom?
The number of protons in the nucleus
The number of neutrons in the nucleus
The total number of protons and neutrons
The number of electrons minus protons
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Why The proton number is the number of protons in the nucleus, and it determines which element the atom is.
3
Multiple choice · Easy
Which particle in the nucleus has no electric charge?
Neutron
Proton
Electron
Alpha particle
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Why The neutron is electrically neutral; the proton carries a positive charge and the electron (not in the nucleus) is negative.
4
Multiple choice · Easy
Isotopes of the same element have the same number of protons but a different number of which particle?
Neutrons
Protons
Electrons
Nuclei
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Why Isotopes differ only in the number of neutrons, so they have the same proton number but different nucleon (mass) numbers.
5
Multiple choice · Easy
Which type of radiation is the most ionising?
Alpha
Beta
Gamma
All ionise equally
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Why Alpha particles are large and highly charged, so they ionise strongly but have very short range; gamma is the least ionising.
6
Multiple choice · Easy
Background radiation always present in the environment can come from which natural source?
Radon gas from rocks and soil
Mobile phone signals
Sunlight reflected from the Moon
Sound waves from the ground
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Why Radon gas from rocks, cosmic rays, and food are natural background sources; nuclear power waste is a man-made contributor.
7
Fill in the blank · Easy
The total number of protons and neutrons in a nucleus is called the
Check answer
Answer:
nucleon / mass
Why The nucleon number (also called the mass number) is the sum of the protons and neutrons in the nucleus.
8
Fill in the blank · Easy
A common instrument used to detect and measure radioactivity is the
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Answer:
Geiger / Geiger-Muller / Geiger Muller / GM
Why A Geiger-Muller (Geiger) counter detects ionising radiation by registering counts when radiation passes through its tube.
9
Multiple choice · Medium
An atom is written as U-235 with a proton number of 92. How many neutrons does it contain?
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Why Neutrons = nucleon number minus proton number = 235 - 92 = 143.
10
Multiple choice · Medium
Which statement correctly describes a beta particle?
A high-speed electron emitted from the nucleus
A helium nucleus
An electromagnetic wave
A slow-moving proton
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Why A beta particle is a fast-moving electron emitted when a neutron changes into a proton in the nucleus.
Key terms in Nuclear physics
Atom: The smallest unit of an element, made of a tiny central nucleus surrounded by orbiting electrons.
Nuclear model of the atom: The model in which an atom has a small dense positively charged nucleus with electrons moving around it at a relative distance.
Nucleus: The tiny central core of an atom that contains protons and neutrons and holds nearly all of the atom's mass.
Proton: A positively charged particle found in the nucleus, each carrying a charge equal and opposite to that of an electron.
Neutron: An uncharged particle found in the nucleus that adds mass but no electric charge to the atom.
Electron: A very light, negatively charged particle that moves around the nucleus in the space surrounding it.
Nucleon: A general name for any particle inside the nucleus, meaning either a proton or a neutron.
Proton number: The number of protons in the nucleus of an atom, which determines which element it is.
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