Science Trivia Questions

What is the chemical symbol for gold?

Answer: Au EasyFrom the Latin aurum.Why?

What is the hardest known natural substance?

Answer: Diamond MediumIt is pure carbon, arranged in a rigid three-dimensional lattice.Why?

What is the lightest element on the periodic table?

Answer: Hydrogen HardA single proton and one electron make up the ordinary atom.Why?

What is the process by which a solid turns directly into a gas?

Answer: Sublimation HardDry ice does this at room temperature, skipping any liquid stage.Why?

What is the pH of pure water at room temperature?

Answer: 7 HardSeven is neutral, neither acidic nor alkaline.Why?

The chemical formula H2O describes which substance?

Answer: Water EasyTwo hydrogen atoms bonded to a single oxygen atom.

The periodic table arranges elements by which property?

Answer: Atomic number MediumAtomic number is simply the count of protons in the nucleus.

Which subatomic particle determines the identity of a chemical element?

Answer: The proton HardChange the neutron count instead and you get an isotope, not a new element.Why?

Which element has the chemical symbol O?

Answer: Oxygen EasyIt is the most abundant element in Earth's crust by mass.

Table salt is a compound of sodium and which other element?

Answer: Chlorine EasyBoth are dangerous on their own, yet together they form something we sprinkle on food.

Which three are the classic states of matter?

Answer: Solid, liquid and gas EasyPlasma is often counted as a fourth, found in stars and lightning.

Which chemical symbol represents sodium?

Answer: Na MediumIt comes from natrium, the Latin name for soda.

Which gas is given off when an acid reacts with a metal such as zinc?

Answer: Hydrogen MediumThe classic test is a lit splint, which makes the gas pop.

Bronze is an alloy of copper and which other metal?

Answer: Tin MediumCopper mixed with zinc makes brass instead.

Which metal has the highest melting point?

Answer: Tungsten HardAt around 3,400 degrees Celsius, it made the ideal filament for incandescent light bulbs.

Sodium bicarbonate is better known in the kitchen as what?

Answer: Baking soda HardBaking powder contains it plus a dry acid, so the two are not interchangeable in recipes.

Avogadro's number is approximately what?

Answer: 6.02 × 10^23 HardIt is the number of particles in one mole of any substance.

A bond in which two atoms share a pair of electrons is called what?

Answer: Covalent bond HardIonic bonds transfer electrons outright, as in table salt.

Which acid gives vinegar its sharp taste?

Answer: Acetic acid HardHousehold vinegar is typically 4 to 8 percent acetic acid in water.

How many bones does an adult human skeleton normally have?

Answer: 206 EasyBabies are born with about 270, which fuse over time.Why?

What gas do plants absorb from the air for photosynthesis?

Answer: Carbon dioxide EasyThey release oxygen as a by-product of the same reaction.Why?

Which organ in the human body produces insulin?

Answer: Pancreas EasyClusters of cells called the islets of Langerhans do the work.Why?

How many chambers does the human heart have?

Answer: Four MediumTwo atria receive blood and two ventricles pump it out.Why?

What does DNA stand for?

Answer: Deoxyribonucleic acid MediumIts double-helix structure was described by Watson, Crick and Franklin's data.Why?

What blood type is known as the universal donor for red blood cells?

Answer: O negative MediumIt carries neither A, B nor Rh D antigens for a recipient to react against.Why?

Which part of the brain controls balance and coordination?

Answer: Cerebellum HardIt sits at the back of the skull, beneath the larger cerebrum.Why?

Which part of a plant normally takes up water from the soil?

Answer: The roots EasyFine root hairs hugely increase the surface area available for absorption.Why?

Which organ pumps blood around the human body?

Answer: Heart EasyIt beats roughly a hundred thousand times in a day.Why?

Which of these animals is a mammal?

Answer: Dolphin EasyDolphins breathe air, are warm-blooded and feed their young milk.

A caterpillar changes into a butterfly through which process?

Answer: Metamorphosis EasyInside the chrysalis most of the larval body is broken down and rebuilt.

Which blood cells carry oxygen around the body?

Answer: Red blood cells MediumThey use haemoglobin, an iron-containing protein, to bind the oxygen.Why?

An animal that eats only plants is described as what?

Answer: Herbivore MediumMany have specialised guts or extra stomachs to break down cellulose.

Which acid is found in the human stomach?

Answer: Hydrochloric acid HardA mucus lining stops the stomach from digesting itself.Why?

Which organelle is described as the powerhouse of the cell?

Answer: Mitochondrion HardIt carries its own small loop of DNA, inherited from the mother.Why?

The bends, suffered by divers surfacing too fast, is caused by bubbles of which gas?

Answer: Nitrogen HardDissolved nitrogen comes out of solution as the surrounding pressure drops.

Which blood vessel type has walls only one cell thick?

Answer: Capillaries HardThat thinness is what allows gases and nutrients to diffuse across.Why?

Which organ is protected by the skull?

Answer: Brain EasyThe adult skull is made of 22 bones that fuse together during childhood.

Which is the largest organ of the human body?

Answer: Skin EasyIn an adult it weighs around 4 kilograms and covers about 2 square metres.

Oranges and lemons are rich in which vitamin?

Answer: Vitamin C EasySailors once ate citrus to prevent scurvy, a disease caused by lacking it.

Including wisdom teeth, how many teeth does an adult human normally have?

Answer: 32 EasyChildren have 20 milk teeth, which start falling out at around age six.

Which pigment gives plants their green colour?

Answer: Chlorophyll MediumIt absorbs red and blue light and reflects green, which is why leaves look that colour.

The spinal cord belongs to which body system?

Answer: Nervous system MediumIt carries signals between brain and body and handles some reflexes without the brain at all.

Insulin regulates the level of what in the blood?

Answer: Glucose MediumToo little insulin lets blood sugar climb, the hallmark of diabetes.

How many pairs of chromosomes does a typical human body cell contain?

Answer: 23 pairs HardThat makes 46 in total, half inherited from each parent.

Which part of the eye controls how much light enters it?

Answer: Iris HardIt widens the pupil in dim light and narrows it in bright light.

Hair and nails are made mainly of which protein?

Answer: Keratin HardThe same protein forms feathers, hooves and horns in other animals.

What is the speed of light in a vacuum, to the nearest round figure?

Answer: 300,000 km per second MediumNothing carrying information can travel faster than this limit.Why?

Which particle carries a negative electric charge?

Answer: Electron HardIts movement through a wire is what we call electric current.Why?

Water freezes at what temperature on the Celsius scale?

Answer: 0 degrees EasyThe same point is 32 degrees on the Fahrenheit scale.

Which instrument is used to look at things far too small to see?

Answer: Microscope EasyCombining two lenses is what pushes magnification past a simple glass.Why?

Sound cannot travel through which of these?

Answer: A vacuum MediumIt needs particles to pass the vibration along, so space is silent.

Which unit measures electrical resistance?

Answer: Ohm MediumOhm's law ties it to voltage and current in a single relationship.Why?

Absolute zero corresponds to what temperature in Celsius?

Answer: About minus 273 degrees HardIt is the point at which particle motion reaches its theoretical minimum.

Which type of electromagnetic radiation has the longest wavelength?

Answer: Radio waves HardLonger wavelength means lower frequency and lower energy per photon.Why?

The half-life of a radioactive isotope describes what?

Answer: Time for half the atoms to decay HardThe rate is statistical, so it holds no matter how much you start with.

Which form of energy is stored in a battery?

Answer: Chemical energy EasyA reaction inside the cell pushes electrons round the circuit once it is connected.

A ramp is an example of which simple machine?

Answer: Inclined plane EasyIt trades a longer distance for a smaller force to raise the same load.

Which colour of visible light has the shortest wavelength?

Answer: Violet MediumRed sits at the long end, which is why sunsets look red once the blue has been scattered away.

A newton is the unit of what?

Answer: Force MediumOne newton accelerates a one-kilogram mass by one metre per second every second.

Which law states that every action has an equal and opposite reaction?

Answer: Newton's third law MediumIt is why a rocket moves forward as exhaust gases are pushed backward.

Frequency is measured in which SI unit?

Answer: Hertz HardOne hertz is one cycle per second.

In the equation E = mc², what does m stand for?

Answer: Mass HardBecause c² is so large, a tiny mass corresponds to an enormous amount of energy.

Which planet is closest to the Sun?

Answer: Mercury EasyIt has no real atmosphere, so its surface swings between extreme heat and cold.Why?

Which force keeps the planets in orbit around the Sun?

Answer: Gravity EasyIts strength falls off with the square of the distance between two bodies.Why?

Which planet is the largest in our solar system?

Answer: Jupiter EasyMore than 1,300 Earths would fit inside it.

Our solar system belongs to which galaxy?

Answer: The Milky Way EasyThe hazy band across the night sky is its disc, seen edge-on from inside.

Which planet is famous for its bright ring system?

Answer: Saturn EasyThe rings are mostly water ice, with pieces ranging from dust grains to house-sized chunks.

A rock from space that survives to reach Earth's surface is called what?

Answer: Meteorite EasyWhile still burning through the atmosphere it is a meteor; only the landed piece is a meteorite.

Roughly how long does sunlight take to reach Earth?

Answer: About 8 minutes MediumThe Sun is about 150 million kilometres away and light covers 300,000 kilometres each second.

Which planet spins almost on its side, with its axis tilted about 98 degrees?

Answer: Uranus MediumEach pole gets around 42 years of continuous sunlight followed by 42 years of darkness.

Why does the Moon shine at night?

Answer: It reflects sunlight MediumThe surface reflects only about 12 percent of the light that hits it, roughly like worn asphalt.

Which is the hottest planet in the solar system?

Answer: Venus MediumIts thick carbon dioxide atmosphere traps heat, making it hotter than Mercury despite being further from the Sun.

Venus rotates in the opposite direction to most planets. What is this called?

Answer: Retrograde rotation HardIts spin is so slow that a day on Venus lasts longer than its year.

After the Sun, which star is closest to Earth?

Answer: Proxima Centauri HardIt lies about 4.2 light years away, a red dwarf too faint to see with the naked eye.

Which object is so dense that not even light can escape its gravity?

Answer: Black hole HardThe boundary beyond which nothing returns is called the event horizon.

The point in a planet's orbit closest to the Sun is called what?

Answer: Perihelion HardEarth reaches it in early January, not in northern summer, which surprises many people.

What is the most abundant gas in Earth's atmosphere?

Answer: Nitrogen EasyIt makes up roughly 78 percent.Why?

Which gas makes up the ozone layer that filters ultraviolet light?

Answer: Ozone MediumOzone is a molecule of three oxygen atoms rather than the usual two.Why?

Which layer of Earth lies directly beneath the crust?

Answer: The mantle MediumSlow convection in it drives the movement of tectonic plates.Why?

Molten rock that erupts from a volcano is called what?

Answer: Lava EasyUnderground it is called magma; the name changes once it reaches the surface.

Which natural event is measured on the Richter scale?

Answer: Earthquakes EasyEach whole step on the scale represents roughly ten times more ground motion.

Clouds are mostly made of what?

Answer: Tiny water droplets and ice crystals EasyWater vapour itself is invisible; a cloud appears only once it condenses into droplets.

Burning fossil fuels adds which greenhouse gas to the atmosphere in the largest amounts?

Answer: Carbon dioxide EasyWater vapour traps more heat overall, but carbon dioxide is the one human activity is adding.

Rock formed from cooled magma or lava is called what?

Answer: Igneous MediumGranite cools slowly underground while basalt cools quickly at the surface.

The supercontinent that existed about 250 million years ago is known as what?

Answer: Pangaea MediumGondwana and Laurasia were the two halves it later split into.

Roughly what share of Earth's surface is covered by water?

Answer: About 71 percent MediumFresh water is under 3 percent of that total, and most of it is locked in ice.

Which scale rates the strength of tornadoes?

Answer: Fujita scale HardSaffir-Simpson is for hurricanes and Beaufort for ordinary wind speed.

Stalactites and stalagmites form in caves carved from which rock?

Answer: Limestone HardSlightly acidic water dissolves the calcium carbonate and redeposits it drip by drip.

A boundary where two tectonic plates slide past each other sideways is called what?

Answer: Transform boundary HardThe San Andreas Fault in California is the best-known example.

Most of the ozone layer sits in which layer of the atmosphere?

Answer: Stratosphere HardAlmost all weather happens below it, in the troposphere.

Which scientist proposed the three laws of motion?

Answer: Isaac Newton MediumHe set them out in the Principia, published in 1687.Why?

Which scientist developed the theory of general relativity?

Answer: Albert Einstein MediumIt describes gravity as the bending of space and time by mass.Why?

Which scientist is credited with formulating the theory of evolution by natural selection?

Answer: Charles Darwin HardAlfred Russel Wallace reached a very similar conclusion independently.Why?

Whose 1543 book argued that Earth orbits the Sun?

Answer: Nicolaus Copernicus EasyDe revolutionibus appeared in the year of his death.

Who first observed the four largest moons of Jupiter, in 1610?

Answer: Galileo Galilei EasyThey are still called the Galilean moons: Io, Europa, Ganymede and Callisto.

Marie Curie is best known for her research into what?

Answer: Radioactivity EasyShe won Nobel Prizes in both physics and chemistry, still the only person honoured in two different sciences.

Who first correctly described the circulation of blood, in 1628?

Answer: William Harvey MediumBefore him it was widely believed the liver made blood that the body then used up.

Who developed the first successful smallpox vaccine?

Answer: Edward Jenner MediumHe used material from cowpox sores, and the word 'vaccine' comes from vacca, Latin for cow.

Gregor Mendel worked out the basic laws of inheritance by breeding which plant?

Answer: Pea plants MediumHe tracked traits like seed shape and colour across thousands of plants in a monastery garden.

Who discovered X-rays in 1895?

Answer: Wilhelm Röntgen HardHe called them X because their nature was unknown, and won the first Nobel Prize in Physics for the work.