50 free Blue trivia questions with answers — trivia quiz, new questions added Aug 2026.
This blue trivia quiz is built around one colour and everything named after it. There are questions on the science of blue (why the sky is blue, why blue eyes have no blue pigment, the first synthetic pigment), on the great blues of art and history (lapis lazuli, ultramarine, Prussian blue, Picasso's Blue Period, Miles Davis's Kind of Blue), on blue animals (the blue whale, the blue-ringed octopus, the blue-footed booby, the blue jay) and on the many things that borrowed the name: Bluetooth, blue jeans, blue cheese, blue chips, blue plaques, blue laws, Blue Peter, Blue Monday, Blue (Da Ba Dee), Blue Man Group, IBM's Big Blue and the blue screen of death. It works as a themed round for a baby shower, a colour-themed party or a pub quiz. Difficulty runs from easy questions about the sky to hard ones about Viking kings and 12-inch singles. Every answer is checked against Wikipedia and cited on the question, so you can see where each fact comes from.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Which optical effect, named for a British physicist, makes the daytime sky and the deep sea look blue?
Rayleigh scattering
Scattering rises with the fourth power of frequency, so short blue wavelengths scatter far more than red.
Q 02Blue light has a dominant wavelength between roughly 450 and how many nanometres?
495
Shorter blues drift towards violet, longer ones towards cyan.
Q 03What was the first artificial pigment, produced in Egypt in the third millennium BC?
Egyptian blue
The Romans used it too; it turns up in the frescoes of Pompeii.
Q 04Which two international organisations chose blue for their flags because of its association with harmony?
The UN and the EU
In languages, blue is usually the last basic colour term to be named, long after black, white and red.
Q 05Ultramarine, the most expensive Renaissance pigment, was ground from which stone?
Lapis lazuli
It was reserved for the robes of the Virgin Mary and at times valued as highly as gold.
Q 06The name 'ultramarine' comes from a Latin phrase meaning what?
Beyond the sea
The lapis came from the Sar-i Sang mines of Badakhshan, worked since the 7th millennium BC.
Q 07Which pharaoh's funeral mask is inlaid with the blue stone from which ultramarine was later made?
Tutankhamun
By the end of the Middle Ages Europe was importing the stone to grind into ultramarine.
Q 08Prussian blue, the first modern synthetic pigment, is the traditional 'blue' in what?
Blueprints
Hokusai used it for his wave prints after it reached Japan through Nagasaki in the 1820s.
Q 09Which artist's Blue Period, from 1901 to 1904, followed the suicide of his friend Carles Casagemas?
Pablo Picasso
He painted beggars, prostitutes and drunks in near-monochrome blues before warming into the Rose Period.
Q 10Blue eyes have no blue pigment; what light phenomenon in the iris stroma gives them their colour?
Tyndall scattering
Mammals are born with blue eyes and any darkening develops afterwards.
Q 11The blue whale is the largest animal ever known; roughly how much can one weigh?
Up to 200 tonnes
A stranded North Atlantic blue whale's heart weighed 180 kg, the largest known in any animal.
Q 12A blue whale's diet consists almost entirely of what?
Krill
An average whale needs about 1,120 kg of krill a day.
Q 13To how low can a blue whale's heart rate fall on a deep dive?
2 beats per minute
On surfacing it climbs to about 37, near its maximum.
The blue-ringed octopus carries enough venom to kill over 20 adult humans, using which toxin?
Q 21The wireless standard's logo binds the runes Hagall and Bjarkan, initials of which Viking king?
Harald Gormsson
The runes come from the Younger Futhark alphabet.
Q 22Blue jeans as we know them date from a patent granted to Jacob Davis and Levi Strauss in which year?
1873
The innovation was copper rivets at the pocket corners.
Q 23Roughly how much indigo dye, almost all of it synthetic, was produced a year as of 2023?
Around 80,000 tonnes
The natural dye came from Indigofera plants, once common worldwide; synthetic indigo has replaced it almost entirely.
Tetrodotoxin
There is no antivenom, and the animal is only 12 to 20 cm long.
Q 15About half of all breeding pairs of blue-footed boobies nest on which islands?
The Galápagos
The blue feet come from diet and are shown off in a high-stepping mating dance.
Q 16The blue jay is a member of which bird group?
The corvids, with crows
Like other corvids it hides acorns to eat later.
Q 17Under the popular definition, when is a full moon called 'blue'?
It is the second in one calendar month
Pruett had misread a 1937 Maine Farmers' Almanac article; his version happens seven times every 19 years.
Q 18How often does a calendrical blue moon occur?
Seven times in 19 years
A genuinely blue-looking moon needs smoke or volcanic ash in the air, hence 'once in a blue moon'.
Q 19Bluetooth technology is named after a 10th-century king of which country?
Denmark
He introduced Christianity to Denmark; the logo merges the runes for his initials H and B.
Q 20Which Intel engineer proposed the name Bluetooth in 1997 after reading about the Viking king?
Jim Kardach
It was meant as a codename but spread through the industry before it could be changed.
Q 24By legend, Roquefort was discovered when a shepherd left his lunch in a cave to chase what?
A beautiful girl
He came back months later to find Penicillium roqueforti had done its work.
Q 25The 'blue chip' stock term comes from which game, where blue chips are traditionally worth most?
Poker
Dow Jones lore credits early employee Oliver Gingold with coining it in the 1920s.
Q 26The term 'blue collar' was first used for trades jobs in 1924 in a newspaper in which US state?
Iowa
'Blue laws', by contrast, restrict business on Sundays for religious reasons.
Q 27London's blue plaque scheme, the first of its kind in the world, was launched in which year?
1866
English Heritage has run it since 1986.
Q 28Blue Peter, on air since 1958, holds what world record?
Longest-running children's TV show
Its most replayed moment is Lulu the baby elephant relieving herself on the studio floor in 1969.
Q 29New Order's 'Blue Monday' holds what sales record?
Best-selling 12-inch single ever
Peter Saville's die-cut sleeve was designed to look like a 5¼-inch floppy disk.
Q 30Which Italian group had a worldwide hit in 1999 with 'Blue (Da Ba Dee)'?
Eiffel 65
It topped the charts in at least 18 countries and entered the UK top 40 on import sales alone.