Sense of Smell
0Loading crowd target
0Loading crowd target
6correct to beat the crowd
50 free Sense of Smell trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Smell is the sense people notice least and miss most. It warns of smoke and spoiled food, shapes most of what we call flavour, and can summon a memory faster than any photograph. The science behind it is younger than you might expect, and full of surprises. This quiz covers olfaction from several angles: how the nose and brain detect and sort odours, what happens when the sense fails, the animals that live by scent, and the chemistry behind smells both lovely and foul. Along the way it visits the perfume trade, some famously pungent foods, and moments when a bad smell changed history. The questions run from easy to challenging, so they suit a family quiz night, a biology class or anyone curious about the human body. Every answer comes with a short explanation, so you will leave knowing why things smell the way they do.
30 of 50 questions with answers and explanations. Play the quiz
Q 01What did Apollo astronauts say Moon dust smelled like when their spacesuits carried it into the cabin?
Gunpowder
Gunpowder is how the moonwalkers described the dust that rode back inside on their suits. Harrison Schmitt of Apollo 17 called his reaction to it lunar hay fever.
Q 02What name did two Australian scientists coin for the earthy scent of rain falling on dry ground?
Petrichor
Petrichor comes from oils that build up in rock and soil during dry spells and are set free by moisture. Isabel Bear and Dick Thomas named it in the journal Nature in 1964.
Q 03Which household fuel has had a rotten-egg odour added ever since a 1937 Texas school explosion?
Natural gas
Natural gas has no smell of its own, so the leak that filled the Texas school went unnoticed. Within weeks of the blast, a sulphur compound was being added as a warning.
Q 04Which spiky Southeast Asian fruit is banned from Singapore's public transport because of its lingering smell?
Durian
Durian is known across the region as the king of fruits. Its odour can hang about for days, so some hotels turn it away as well.
Q 05Which mammal carries nearly 2,000 working smell-receptor genes, about five times as many as humans have?
African elephant
The African elephant has more than twice as many of these genes as a dog. Researchers in Tokyo found the total when they compared thirteen mammal species.
Q 06Which waxy substance from the gut of sperm whales was long prized for making perfume last longer?
Ambergris
Ambergris is thought to form around the sharp beaks of squid that the whale has swallowed. Perfume makers now mostly use a synthetic substitute.
Q 07Which green spring vegetable contains a sulphur compound that gives urine a strong smell soon after eating?
Asparagus
Asparagus owes the effect to asparagusic acid, a sulphur compound found in no other vegetable. A French treatise on food was already remarking on the smell in 1702.
Q 08Which children's modelling compound had its signature scent registered as a trademark by Hasbro in 2018?
Play-Doh
Play-Doh began life in 1930s Cincinnati as a putty for wiping coal soot off wallpaper. It was relaunched as a toy once demand for the cleaner had shrunk.
Q 09Which Sumatran plant heats its towering flower spike to spread a stench of rotting flesh?
Titan arum
The titan arum warms its spike to about human body temperature, which helps the smell reach the carrion insects that pollinate it. Each bloom lasts only a day or so.
Q 10Which large hunting dog breed has been used to track people by scent since the Middle Ages?
Bloodhound
The bloodhound was first bred to hunt deer and wild boar. Medieval Scottish stories tell of sleuth hounds being put on the trail of Robert the Bruce.
Q 11What is the medical term for a total loss of smell, a widely reported symptom of COVID-19?
Anosmia
Anosmia is risky as well as dulling, because it hides gas leaks, smoke and spoiled food. People who have it can still taste, but the flavours of a meal go missing.
Q 12Which German city gave its name to a citrus fragrance first mixed there by Giovanni Maria Farina?
Cologne
Cologne became the perfume's name because Farina, an Italian, wanted to honour his new hometown. He wrote to his brother that the scent recalled an Italian spring morning after rain.
Q 13Which prized underground fungi were pigs traditionally used to sniff out beneath oak and hazel trees?
Truffles
Truffles are now mostly hunted with trained dogs, because a pig tends to eat what it finds. Tests in 1990 found that both animals home in on dimethyl sulfide in the fungi's scent.
Q 21What are chemical signals called, such as the airborne lure a female silkworm moth releases to attract mates?
Pheromones
Pheromones got their name in 1959, just after the German biochemist Adolf Butenandt identified the silkworm moth's lure, bombykol, as the first known example.
Q 22Which animal's spray is best removed with hydrogen peroxide and baking soda rather than tomato juice?
Skunk
Skunk spray gets its stench from sulphur compounds, which the peroxide mix turns into odourless acids. The chemist Paul Krebaum devised the recipe in 1993.
Q 23Which toxic gas smells of rotten eggs at first but quickly deadens the sense of smell?
Hydrogen sulfide
Q 14Which famous perfume did Ernest Beaux create in 1921 using aldehydes to boost its floral scent?
Chanel No. 5
Chanel No. 5 kept the number of the sample that Coco Chanel picked from the glass vials Beaux set before her. She said the number five would bring good luck.
Q 15Which flightless New Zealand bird is the only bird with nostrils at the very tip of its beak?
Kiwi
The kiwi probes the ground with its long beak for worms and insects it cannot see. A keen sense of smell is unusual among birds.
Q 16Which aromatic resin from Boswellia trees was one of the gifts the Magi brought to the infant Jesus?
Frankincense
Frankincense is tapped from the trees two or three times a year, and the last taps give the most fragrant drops. Most of the world's supply now comes from the Horn of Africa.
Q 17Which sour citrus fruit, a staple of perfumery, gives Earl Grey tea its distinctive aroma?
Bergamot
Bergamot oil comes from the fruit's skin, and most of Italy's crop grows on one short stretch of the Calabrian coast. The fruit is thought to be a cross of lemon and bitter orange.
Q 18Which fish is thought to use smell to find the very stream where it hatched years earlier?
Salmon
Salmon are thought to cross the open ocean by sensing the Earth's magnetic field, then follow the scent of their home river for the final stretch.
Q 19Which herb of the mint family gives off nepetalactone, a compound that repels mosquitoes, cockroaches and termites?
Catnip
Catnip leaves about a third of cats completely unmoved. Leopards, cougars and lynxes have reacted to it much as pets do, while lions and tigers respond less reliably.
Q 20Which medical word for bad breath became widely known through 1920s advertisements for Listerine mouthwash?
Halitosis
Halitosis was coined by the physician Joseph William Howe in a book of 1874, decades before the mouthwash adverts turned it into a household worry.
Hydrogen sulfide is so dangerous because the nose stops registering it, leaving victims unaware until it is too late. In tiny amounts it also helps give flatulence its smell.
Q 24Which poisonous gas from car exhausts, nicknamed the silent killer, has no smell, colour or taste?
Carbon monoxide
Carbon monoxide earned the nickname among miners, who also called it whitedamp. It forms whenever a fuel such as wood, coal or petrol burns without enough air.
Q 25Which pungent gas do smelling salts release to jolt a person who has fainted back to alertness?
Ammonia
Ammonia inhalants are now banned in most boxing competitions, for fear the jolt could mask a serious injury. Some Victorian constables carried them to revive fainting women.
Q 26Which city endured the Great Stink of 1858, when a reeking river nearly drove its parliament out?
London
London answered with Joseph Bazalgette's sewers, which carried the waste away from the Thames. Parliament's riverside curtains had been soaked in lime chloride to mask the smell.
Q 27Which mosquito-borne disease takes its name from the Italian for bad air, once blamed for causing it?
Malaria
Malaria kept the name even after Ronald Ross proved in 1897 that mosquitoes, not foul marsh vapours, carry the parasite. It had also been known as marsh fever.
Q 28Who in 17th-century Europe wore long beaked masks stuffed with herbs and dried flowers?
Plague doctors
Plague doctors hoped the scents would shield them from disease carried on the air. Despite its popular image, the beaked costume is not known from the medieval Black Death.
Q 29Which kitchen bulb lingers on the breath because a sulphur compound from it is exhaled through the lungs?
Garlic
Garlic breath comes from allyl methyl sulfide, which passes from the blood to the lungs and out through the skin as well. Sipping milk with the meal has been shown to reduce it.
Q 30Which pungent cheese is ripened by a bacterium that also lives on human skin and causes foot odour?
Limburger
Limburger smells so much like feet that mosquitoes are drawn to both equally, a finding that won an Ig Nobel Prize in 2006.