Getting your questions ready
Getting your questions ready
Beat the crowd
10 questions No timer
50 free Oxygen trivia questions with answers — science & nature quiz, new questions added Aug 2026.
This oxygen trivia quiz covers the element we breathe and the most abundant one in Earth's crust. The easy questions handle the basics: its symbol and atomic number, how much of the air it makes up, what ozone is, where atmospheric oxygen comes from and who gets credit for discovering it. The harder end digs into the science and the history: why Lavoisier's name for it was based on a mistake, the alchemist who isolated it before 1604, why liquid oxygen is sky blue and sticks to a magnet, the Great Oxygenation Event 2.45 billion years ago, oxygen-18 and ancient climates, how much steelmaking consumes, why the Apollo 1 fire spread so fast, oxygen toxicity for divers, and how airliner masks make their own supply. Every answer was checked against the element's encyclopaedia entry before publishing and the supporting sentence is stored with each question. Our hydrogen, carbon, periodic table and chemistry quizzes are the natural next stop.
30 of 50 questions with answers and explanations. Play the quiz
Q 01What is oxygen's atomic number?
8
Its symbol is O and it belongs to the chalcogen group of the periodic table.
Q 02Roughly what fraction of Earth's atmosphere is oxygen gas, by volume?
About 21%
Nitrogen makes up most of the rest; the oxygen figure has swung a great deal over geological time.
Q 03Oxygen is the most abundant element in which part of the Earth?
The crust
It makes up 49.2% of the crust by mass, locked in oxides such as silica and iron oxide.
Q 04Oxygen ranks where in abundance in the universe?
Third
Only hydrogen and helium are more common; about 0.9% of the Sun's mass is oxygen.
Q 05What is the chemical formula of ozone?
O3
This reactive allotrope absorbs UVB and UVC in the stratosphere but is a corrosive pollutant at ground level.
Q 06Ozone is produced in the upper atmosphere when O2 combines with what?
Atomic oxygen split off by ultraviolet light
At low Earth orbit there is enough atomic oxygen to corrode spacecraft.
Q 07Priestley is usually given priority over Scheele for discovering oxygen. Why?
His work was published first
Scheele had made the gas by 1773 or earlier in Uppsala, but sat on the results; Priestley published in 1775.
Q 08What did Priestley call the gas he liberated from mercuric oxide in 1774?
Dephlogisticated air
He noticed candles burned brighter in it and that a mouse lived longer; breathing it himself, he felt 'peculiarly light and easy'.
Q 09Scheele published in 1777 and gave the gas what name?
Fire air
He had made it by heating mercuric oxide and nitrates in 1771-72 but sat on the results because they clashed with phlogiston theory.
Q 10Which Polish alchemist isolated oxygen before 1604 and called it 'cibus vitae', the food of life?
Michael Sendivogius
He recognised it as the gas released when potassium nitrate decomposes, but contemporaries like Boyle missed the point.
Q 11Who first recognised oxygen as an element and correctly explained its role in combustion, in 1777?
Antoine Lavoisier
His quantitative experiments with tin in a sealed container demolished the phlogiston theory.
Q 12Lavoisier's name 'oxygene' comes from Greek roots meaning what?
Acid producer
He wrongly believed every acid contained it; Humphry Davy showed in 1812 that hydrogen chloride does not, but the name stuck.
Q 13A poem titled 'Oxygen' in The Botanic Garden (1791) helped the word enter English. Who wrote it?
Erasmus Darwin
Charles Darwin's grandfather championed the French name over English objections.
Q 21Why does normal 'triplet' oxygen react only slowly with most organic molecules?
Its two unpaired electrons clash with their paired spins
This quirk is what prevents spontaneous combustion of everything around us.
Q 22How many stable isotopes does oxygen have?
Three
Oxygen-16 dominates at 99.76%; the ratio of oxygen-18 to oxygen-16 in shells and ice cores reveals ancient climates.
Q 23Paleoclimatologists read past temperatures from the ratio of oxygen-18 to oxygen-16 in what?
Marine shells, skeletons and ice cores
Q 14What did Lavoisier call the part of air that supports neither combustion nor respiration?
Azote
From the Greek for 'lifeless', it became nitrogen in English but kept the old name in French.
Q 15John Dalton assumed water was HO, so he thought oxygen's atomic mass was how many times hydrogen's?
8
Gay-Lussac and Humboldt showed in 1805 that water is two volumes of hydrogen to one of oxygen, and Avogadro sorted out the rest by 1811.
Q 16Which two Polish scientists first liquefied oxygen in a stable state, in March 1883?
Zygmunt Wróblewski and Karol Olszewski
Pictet and Cailletet had each made a few drops in December 1877, too little to study.
Q 17Who flew the first liquid-fuelled rocket in 1926, burning gasoline with liquid oxygen?
Robert H. Goddard
It flew 56 metres at 97 km/h from a field in Auburn, Massachusetts.
Q 18What colour are liquid and solid oxygen?
Light sky blue
The tint comes from absorption in the red, unlike the sky's blue, which is Rayleigh scattering.
Q 19Liquid oxygen can be held between the poles of a strong magnet because it is what?
Paramagnetic
The unpaired electrons in triplet O2 give it magnetic character, exploited in paramagnetic oxygen analysers.
Q 20At roughly what temperature does oxygen condense to a liquid?
About 90 K
That is about -183 C; it freezes at about 54 K.
Lighter oxygen-16 water evaporates faster, so cold periods leave seawater and shells richer in oxygen-18.
Q 24Which crashed spacecraft returned solar-wind samples showing the Sun has more oxygen-16 than Earth?
Genesis
The result implies some unknown process stripped oxygen-16 from the disc of material that formed Earth.
Q 25What process produces the free oxygen in Earth's atmosphere?
Photosynthesis
Marine algae and cyanobacteria may provide around 70% of it; without constant replenishment the reactive gas would vanish from the air.
Q 26Oxygen began accumulating in the atmosphere about 2.45 billion years ago in an episode known as what?
The Great Oxygenation Event
Levels stayed below 10% of today's; a second rise around 500 million years ago pushed them to modern values.
Q 27Which molecule in red blood cells binds O2, turning from bluish red to bright red?
Hemoglobin
Molluscs use hemocyanin and spiders and lobsters use hemerythrin instead; a litre of blood can carry up to 200 cm3 of O2.
Q 28Roughly how much oxygen does a resting adult inhale per minute?
About 2 grams
Across humanity that adds up to more than 6 billion tonnes a year.
Q 29Which industry consumes 55% of commercially produced oxygen?
Steelmaking
O2 is lanced into molten iron to burn off sulfur and excess carbon, pushing temperatures to 1,700 C.
Q 30Ethylene reacted with oxygen gives ethylene oxide, which becomes ethylene glycol, the feedstock for what?
Antifreeze and polyester
The chemical industry as a whole takes about 25% of commercial oxygen.