Physical Science Trivia
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100 free Physical Science trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Physical science is the half of the school syllabus that explains the world you can push, drop, heat and wire up: why a feather and a hammer fall alike on the Moon, why ice floats, why a compass points where it does, and what a volume knob actually changes in a sound wave. These fifty questions follow the course as it is usually taught, from states of matter and the periodic table through forces and motion, work and simple machines, sound and light, circuits and magnets, chemical reactions, and a few basics of Earth and space. Every answer comes with the one-line reason that makes it stick. It suits a middle- or high-school revision session, a homeschool test, or a pub quiz science round for anyone who remembers the lessons but not quite the answers.
30 of 100 questions with answers and explanations. Play the quiz
Q 01Stars are almost pure balls of which state of matter, which makes up over 99% of the visible universe?
Plasma
Plasma forms when atoms are stripped of their electrons, which is why it conducts electricity and glows in neon signs and lightning bolts.
Q 02When Apollo 15's David Scott dropped a hammer and a falcon feather side by side on the Moon, what happened?
They landed together
They landed together because the Moon has almost no atmosphere, so no drag slowed the feather, exactly as Galileo had predicted centuries earlier.
Q 03Lakes freeze from the top down because liquid water is at its densest at roughly what temperature?
4 °C
4 °C is where water is heaviest, so the colder water near freezing floats on top and ice forms there first, leaving fish alive underneath all winter.
Q 04An 80 kg astronaut keeps the same mass on the Moon, but their weight there drops to roughly what fraction of Earth's?
One sixth
One sixth is the figure because gravity on the Moon is only about 1.6 m/s², which is why astronauts in moonwalk footage seem to bounce across the surface.
Q 05Ice is only slightly less dense than seawater, so roughly how much of a floating iceberg sits below the waterline?
About 90%
About 90% of an iceberg is hidden underwater, which is why 'tip of the iceberg' came to mean the small visible part of a much bigger problem.
Q 06Through which of these does sound travel fastest?
Iron
Iron carries sound at about 5,100 m/s, because sound moves faster the stiffer the material; fresh water manages only about 1,500 m/s.
Q 07Mixing red, green and blue light at full strength, as the pixels of a TV screen do, produces which colour?
White
White is what all three light primaries add up to, the reverse of paint, where every pigment absorbs some light, so mixing them all heads towards black.
Q 08Gravity on the International Space Station is still 90% of Earth's, so why do the crew float?
They are in constant free fall
They are in constant free fall, along with the station itself, which is moving sideways so fast that it keeps missing the Earth as it drops toward it.
Q 09Dry ice used for stage fog leaves no puddle because solid carbon dioxide turns straight into gas, a change called what?
Sublimation
Sublimation skips the liquid stage entirely: under ordinary conditions carbon dioxide has no liquid form, so the solid simply vanishes into gas at −78.5 °C.
Q 10Which particle's count in the nucleus, the same for all an element's isotopes and ions, fixes its atomic number?
Protons
Protons put the periodic table in order: Mendeleev placed tellurium ahead of lighter iodine on chemical instinct, and sorting the elements by proton count later proved him right.
Q 11Helium, neon and argon, which almost never form compounds, make up which group on the far right of the periodic table?
Noble gases
Noble gases were long called the inert gases because their full outer electron shells leave them nothing to gain from bonding; the first compound of one was only made in 1962.
Q 12Lithium, sodium and potassium, which fizz or even burst into flame when dropped in water, form which group of elements?
Alkali metals
Alkali metals get more violent the further down the group you go: potassium reacts violently at room temperature, and caesium explodes even in cold water.
Q 13Silicon and germanium, the elements behind computer chips, sit on the periodic table's zigzag line as which class?
Metalloids
Q 21Which of Isaac Newton's laws explains how a rocket accelerates in empty space, where there is nothing to push against?
The third law
The third law says every action has an equal and opposite reaction: the rocket throws hot gas backwards, and the gas pushes the rocket forwards just as hard.
Q 22A skydiver stops speeding up once air resistance balances their weight; what is this steady top speed called?
Terminal velocity
Terminal velocity is reached when drag exactly cancels weight, so a skydiver falls at a steady rate until the parachute opens and a far slower balance is struck.
Q 23Tripling the gap between two masses cuts their gravitational pull to what fraction?
One ninth
Metalloids are only fair conductors of electricity, which is exactly what makes silicon useful: its conductivity can be tuned, the basis of every transistor.
Q 14Which chemists' counting unit is celebrated every 23 October from 6:02 am, a nod to the 6.02 × 10²³ particles it holds?
Mole
Mole Day grew from one high-school chemistry teacher's classroom celebration: an article on it in The Science Teacher inspired Maurice Oehler to found the National Mole Day Foundation in 1991.
Q 15On the pH scale, usually given as running from 0 to 14, pure water at 25 °C sits at which value?
7
7 is neutral only at 25 °C: warm the water and its neutral point slips below 7, while staying neutral, because more molecules split into ions.
Q 16Instant cold packs for sports injuries chill because dissolving ammonium nitrate in water is which kind of process?
Endothermic
Endothermic processes pull heat in from their surroundings, so the pack drops to near freezing moments after the inner water bag is burst.
Q 17Platinum in a car's exhaust converter cleans the fumes by playing which chemical role?
Catalyst
Catalysts speed up reactions without being used up, so a converter needs only a few grams of platinum, which is still valuable enough that thieves cut converters off cars.
Q 18Galvanised steel, whose coating corrodes in place of the iron beneath it, owes its rust resistance to which metal?
Zinc
Zinc acts as a sacrificial layer, corroding first so that even a scratched coating keeps protecting the steel, which is why galvanised buckets and railings last for decades.
Q 19In table salt, each sodium atom hands one electron to a chlorine atom, forming which type of chemical bond?
Ionic
Ionic bonds are the pull between the charged ions left behind, which lock into a rigid lattice, so salt forms hard, brittle crystals that shatter rather than bend.
Q 20Which property, described by Newton's first law, makes standing bus passengers lurch forward when the bus brakes?
Inertia
Inertia means the passengers simply keep moving at the bus's old speed while the bus itself slows beneath them, which is also why seat belts exist.
One ninth, because three squared is nine: gravity thins out over an ever-larger sphere as the distance grows, so it fades fast but never quite reaches zero.
Q 24Big Ben's pendulum beats once every two seconds, a rate set chiefly by which property of the pendulum?
Its length
Its length sets the beat, which is how Big Ben is fine-tuned: each old penny stacked on the pendulum raises its centre of mass, shortens its effective length and speeds the clock by 0.4 seconds a day.
Q 25A sharp knife cuts better than a blunt one because the same push on a smaller edge gives more of what?
Pressure
Pressure rises as the same force is squeezed onto a smaller patch, which is also why a thumbtack's point sinks into a wall while its flat head does nothing.
Q 26A loading ramp is the simplest form of which classical simple machine, of which a screw is a wrapped-around version?
Inclined plane
Inclined planes trade distance for force: moving a load up a long gentle slope takes less effort than lifting it straight up, which is why mountain roads switchback.
Q 27Which tool is a second-class lever, with the load between the pivot and the effort, just like a wheelbarrow?
Nutcracker
Nutcrackers, like bottle openers and wheelbarrows, always multiply force, because the load sits closer to the pivot than your hands do.
Q 28By which method of heat transfer does the Sun's energy cross 150 million km of empty space to reach Earth?
Radiation
Radiation needs no medium, so it alone crosses the vacuum of space. A vacuum flask turns that around: its empty gap blocks conduction and convection, and its silvered walls reflect radiation.
Q 29Which spring law is named for the 17th-century English scientist who also coined the biological word 'cell'?
Hooke's law
Hooke's law says a spring's stretch is proportional to the force on it, a discovery Robert Hooke first announced as a scrambled Latin anagram to stake his claim.
Q 30Which part of the electromagnetic spectrum has the longest wavelengths, some of them larger than a planet?
Radio waves
Radio waves in the AM band reflect off the ionosphere after dark, which is why stations hundreds of miles away can be picked up at night but not by day.