Radioactivity
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50 free Radioactivity trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Radioactivity is the rare bit of physics that most people meet in everyday life: in a hospital scan, on a museum label giving the age of a mummy, or in a news story about a reactor. Unstable atoms break down on a schedule that nothing can speed up or slow down, and what they fire out as they go has been healing, dating and occasionally harming things for more than a century. This quiz covers the ground a radioactive decay test usually does: what alpha, beta and gamma radiation are and what stops each one, how a nucleus changes when it decays, half-lives and decay chains, and the units and instruments used to measure a dose. Around that core are the people who made the discoveries and the stranger corners of the subject, from glowing watch dials to foods that are slightly radioactive. The early questions suit middle school science and curious beginners, and the later ones will stretch students revising nuclear physics. Every answer has a short explanation, so the quiz works as a revision aid as well as a trivia round.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Which scientist coined the word radioactivity and is the only person to win Nobel Prizes in two different sciences?
Marie Curie
Marie Curie took the physics prize in 1903 and the chemistry prize in 1911. Her notebooks, and even her cookbooks, are still radioactive.
Q 02Which glowing element did American factory women paint onto watch dials in the 1920s before suing over their poisoning?
Radium
Radium was in the luminous paint, and the women were told to sharpen their brushes on their lips. Their lawsuits brought major improvements in industrial safety.
Q 03Which fruit gives its name to an informal unit of radiation dose because of the potassium it naturally contains?
Banana
Banana equivalent dose compares an exposure to eating one banana, whose potassium-40 is very slightly radioactive. The body sheds surplus potassium, so the dose never builds up.
Q 04Which isotope, with a half-life of about 5,730 years, lets archaeologists date ancient wood, bone and cloth?
Carbon-14
Carbon-14 is taken up by every living thing until it dies, and then the clock starts ticking. Willard Libby won the 1960 Nobel Prize in Chemistry for the method.
Q 05Which nuclear power plant's 1986 reactor explosion forced the permanent evacuation of the nearby city of Pripyat?
Chernobyl
Chernobyl's reactor 4 exploded on 26 April 1986. Pripyat's 49,000 or so residents were bussed out the next day, and the city has stood empty ever since.
Q 06A speck of radioactive americium-241 ionises the air inside which common household safety device?
Smoke detector
A smoke detector of the ionisation type relies on alpha particles to keep a tiny current flowing through its chamber. Smoke drifting in disturbs the current and trips the alarm.
Q 07Which famous thought experiment uses one radioactive atom's random decay to trigger a flask of poison in a sealed box?
Schrödinger's cat
Schrödinger's cat is, in theory, both alive and dead until someone opens the box. Erwin Schrödinger devised the puzzle in 1935 while debating quantum mechanics with Albert Einstein.
Q 08What colour is the Cherenkov glow that surrounds highly radioactive fuel rods stored underwater in a reactor pool?
Blue
Blue light appears because charged particles from the fuel move through the water faster than light does there. Pavel Cherenkov shared the 1958 Nobel Prize in Physics for detecting it.
Q 09Which radioactive gas seeps from rock into basements and ranks second only to smoking as a cause of lung cancer?
Radon
Radon has no colour or smell, so only a test kit reveals it. It is denser than air, which is why it collects in basements and crawl spaces.
Q 10Which element, named after its discoverer's homeland, killed former Russian agent Alexander Litvinenko in London?
Polonium
Polonium-210 killed him three weeks after he fell ill, the first confirmed death of its kind. The element honours Poland, birthplace of the scientist who found it in 1898.
Q 11The three classic types of nuclear radiation are named after the first three letters of which alphabet?
Greek
Greek letters alpha, beta and gamma were handed out in rising order of penetrating power. Alpha rays are the easiest to block and gamma rays the hardest.
Q 12An alpha particle carries a charge of plus two and is identical to the nucleus of which light element?
Helium
Helium nuclei are what alpha particles really are, and most of the helium on Earth began that way. It builds up underground as heavy elements decay and collects in natural gas fields.
Q 13A beta-minus particle, which a few millimetres of aluminium will stop, is identical to which subatomic particle?
Electron
Q 21Uranium-238 emits an alpha particle and becomes which element, named after a Norse god?
Thorium
Thorium honours Thor, the god of thunder. The thorium-234 made this way is unstable too, the first of many steps in a long decay chain.
Q 22Potassium-40 decays into which noble gas, a clock geologists use to date ancient volcanic rock?
Argon
Argon escapes from molten rock but starts to build up once the rock hardens, so the clock starts at zero. Nearly all the argon in the air came from this decay.
Q 23In beta-minus decay, which particle in the nucleus transforms, moving the atom one place up the periodic table?
Neutron
Neutron becomes proton in this decay, and a beta particle flies out to balance the charge. The atom's mass barely changes, yet it is now a different element.
Electron is the everyday name for a beta-minus particle, but it is not waiting inside the nucleus beforehand. It is created at the instant of decay and leaves at tremendous speed.
Q 14Which dense metal is the standard shield against gamma rays and also the stable end point of uranium's decay chain?
Lead
Lead is where all three natural decay chains finish, each at its own stable isotope. Its density also makes it the usual lining for containers of radioactive material.
Q 15Which part of the human body is enough to stop alpha particles, which is why they mainly harm when swallowed or inhaled?
Skin
Skin stops them within about 40 micrometres, only a few cells deep. Inside the lungs or gut there is no such barrier, so the same particles strike living tissue directly.
Q 16Which radiation detector clicks faster as a radioactive source gets closer?
Geiger counter
Geiger counter clicks each mark one ionising event inside a gas-filled tube. The principle dates from 1908, but a practical instrument had to wait for an improved tube in 1928.
Q 17Wilhelm Röntgen's 1895 discovery of which radiation prompted the experiments that revealed radioactivity months later?
X-rays
X-rays made physicists wonder whether glowing minerals gave off something similar. Tests with uranium salts in early 1896 showed they darkened photographic plates with no sunlight at all.
Q 18Which French physicist, namesake of the SI unit of radioactivity, found that uranium salts fog photographic plates?
Henri Becquerel
Henri Becquerel owed the discovery to bad weather: on two overcast days he left his plates in a dark cabinet, and they fogged anyway. One becquerel is one decay per second.
Q 19Which New Zealand-born physicist named alpha and beta rays and later showed that atoms have a tiny, dense nucleus?
Ernest Rutherford
Ernest Rutherford coined the two names in 1899 and proposed the nucleus in 1911, after alpha particles were seen bouncing off thin gold foil. He is called the father of nuclear physics.
Q 20After a reactor accident, tablets of stable iodine are handed out to protect which gland from radioactive iodine?
Thyroid
Thyroid tissue soaks up iodine to make hormones and cannot tell the stable kind from the radioactive kind. Filling it with harmless iodide first means iodine-131 is flushed away instead.
Q 24Wolfgang Pauli proposed which almost massless particle to explain energy that seemed to vanish during beta decay?
Neutrino
Neutrino means little neutral one in Italian. About 65 billion of them from the Sun pass through every square centimetre of you each second.
Q 25PET scanners detect the gamma rays released when which particle, emitted in beta-plus decay, is annihilated?
Positron
Positron is the P in PET. Each one meets its ordinary-matter twin almost at once, and the pair vanish into two gamma rays flying in opposite directions.
Q 26School demonstrations block alpha particles with a single sheet of which material, saving aluminium for beta rays?
Paper
Paper is enough because an alpha particle is heavy and doubly charged, so it gives up its energy quickly. Even in air it travels only a few centimetres.
Q 27Which quantity, written as a superscript to the left of an element's symbol, falls by four in alpha decay?
Mass number
Mass number counts every particle in the nucleus, and an alpha particle carries off four of them. The atomic number falls by only two, so the atom moves two places down the periodic table.
Q 28Physicists call a decaying radioactive nucleus the parent, so which family word names the new nuclide it becomes?
Daughter
Daughter nuclides are often radioactive themselves, and what they decay into is called a granddaughter. A long run of such generations makes up a decay chain.
Q 29Which of the four fundamental forces of nature is responsible for the beta decay of radioactive atoms?
Weak force
Weak force is the only one of the four that can change one type of quark into another. That swap is what turns a decaying atom into a different element.
Q 30George Gamow explained how alpha particles escape a nucleus with which quantum effect, also vital to fusion in stars?
Tunnelling
Tunnelling gives a trapped alpha particle a tiny chance of turning up outside an energy barrier it could never climb. Gamow's theory also showed why faster particles mean shorter half-lives.