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50 free Physical Science trivia questions with answers — science & nature quiz, new questions added Aug 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 50 questions with answers and explanations. Play the quiz
Q 01Stars are almost pure balls of which state of matter, estimated to be 99.9% of all ordinary matter in the universe?
Plasma
Plasma is a gas so hot its atoms have been stripped of 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, so a suited astronaut could bound along despite carrying 80 kg of kit.
Q 05Ice is roughly 10 percent less dense than seawater, so how much of a floating iceberg sits below the waterline?
About 90%
About 90% of an iceberg is hidden underwater, which is why the Titanic's lookouts saw only a small peak and why 'tip of the iceberg' means what it does.
Q 06Sound moves at 343 m/s in air; through fresh water at 20 °C it travels roughly how much faster?
About four times as fast
About four times as fast, at 1,481 m/s, which is why whales can call across whole ocean basins and why sonar works so well underwater.
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 opposite of paint, where mixing every colour in the box gives a muddy dark brown.
Q 08Gravity at the International Space Station is still nine-tenths of its strength on the ground, 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 carry the nucleus's positive charge, and every atom with six of them is carbon, however many neutrons it has packed in alongside.
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 23Under the inverse-square law, tripling the gap between two masses cuts their gravitational pull to what fraction?
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's 6:02 on 10/23 spells out Avogadro's number, and one mole of any substance is the same headcount of particles, from water to uranium.
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 plays which role, speeding up reactions while coming through them unchanged?
Catalyst
Catalysts are not consumed by the reactions they speed up, which is why a few grams of platinum and rhodium can clean a car's exhaust for its whole working life.
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
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 is 4 m long to give a two-second beat, because a pendulum's period is set chiefly by what?
Its length
Its length is all that matters for small swings, and the bob's mass makes no difference, so a clock is sped up by shortening the pendulum and slowed by lengthening it.
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 at all, which is why the Sun's warmth arrives across a vacuum where conduction and convection are both impossible.
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, from a rice grain's width of a millimetre up?
Radio waves
Radio waves also carry the lowest frequencies in the spectrum, below 300 gigahertz, and AM, FM and Wi-Fi all live somewhere in that enormous band.