Molybdenum
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40 free Molybdenum trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Molybdenum is one of those elements almost nobody can spell and almost everybody depends on. It toughens the steel in bridges, bikes and engines, it sits inside enzymes that keep plants and people alive, and it has a longer and stranger history than its tongue-twister name suggests. This quiz turns the best molybdenum fun facts into 40 multiple-choice questions. They cover where the name comes from, who discovered and isolated the metal, the mines and wars that made it valuable, its part in medicine and nutrition, and a few oddities from space, sport and the kitchen. It is pitched at curious adults, chemistry students revising the periodic table, and quiz hosts who want a science round with stories attached. Every answer comes with a short explanation.
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Q 01Molybdenum is named after the ancient Greek word for which metal, whose ores looked similar?
Lead
Lead, molybdos in Greek, lent its name because miners could not tell soft grey molybdenite from galena, the common ore of that heavier metal.
Q 02Which author made molybdenum's atomic number famous as a supercomputer's answer to everything?
Douglas Adams
Douglas Adams picked 42 for Deep Thought's answer in The Hitchhiker's Guide to the Galaxy purely as a joke. Every molybdenum atom happens to carry 42 protons.
Q 03Molybdenum-99 generators, 'milked' for a hospital isotope, are nicknamed after which animal?
Cow
Cow is the nickname, usually 'moly cow', because the decaying molybdenum keeps refilling the generator, which can be milked again about every six hours.
Q 04Molybdenum steel went into which giant German howitzer of World War I?
Big Bertha
Big Bertha hurled shells of about a ton, and its makers chose molybdenum steel because the heat of the propellant was too much for ordinary gun steel.
Q 05A 14th-century sword from which country reportedly holds molybdenum, long before the metal was known?
Japan
Japan forged the blade around 1330. If its molybdenum was added on purpose, as reported, the practice never spread and was later lost.
Q 06Molybdenite, molybdenum's main ore, marks paper so well that it was long mistaken for which mineral?
Graphite
Graphite and molybdenite look and feel so alike that telling them apart reliably takes laboratory equipment. The giveaway is that molybdenite is much denser.
Q 07Peasants at Knaben who found molybdenum ore first traded it pound for pound for which farm food?
Butter
Butter set the first known price of molybdenum ore, one pound for one pound. Once armies wanted the metal, the same weight of ore fetched three times as much.
Q 08Bacteria in the roots of clover and beans use a molybdenum enzyme to capture which gas from the air?
Nitrogen
Nitrogen is turned into ammonia by nitrogenase, an enzyme with a molybdenum atom at its working centre. Without the metal, far less of the gas would ever reach living things.
Q 09X-ray tubes with molybdenum targets are the classic choice in machines screening for which disease?
Breast cancer
Breast cancer screening relies on them because molybdenum gives off low-energy X-rays of about 17 to 20 keV, which show fine detail in soft tissue at a low dose.
Q 10Which US state has the Climax mine, which once supplied three quarters of the world's molybdenum?
Colorado
Colorado's Climax mine sits about 11,360 feet up on Fremont Pass, on a deposit a prospector claimed in 1879 without knowing what the grey mineral was.
Q 11Which symbol stands for molybdenum on the periodic table, where it sits directly beneath chromium?
Mo
Mo is the symbol for molybdenum in group 6. Mn belongs to manganese and Md to mendelevium, while Mb is not an element at all.
Q 12In both world wars, molybdenum stood in for which scarcer metal used to harden tool steel?
Tungsten
Tungsten ran short in both wars, so steelmakers swapped in molybdenum. The M in high-speed steel grades such as M2 still marks the substitute.
Q 13Much molybdenum is a byproduct of mining which metal, as at Chile's vast Chuquicamata pit?
Copper
Copper and molybdenum occur together in huge low-grade deposits, so pits such as Bingham Canyon in Utah sell molybdenum as a valuable sideline.
Q 21People very short of molybdenum react badly to which preservatives, common in wine and dried fruit?
Sulfites
Sulfites are normally made harmless by sulfite oxidase, one of only four human enzymes that need molybdenum. Without the metal the enzyme stalls and the preservatives build up.
Q 22In a part of Armenia with molybdenum-rich soil, heavy intake brought symptoms of which joint disease?
Gout
Gout-like aches appeared because a molybdenum enzyme, xanthine oxidase, makes uric acid, and the villagers' blood carried abnormally high levels of it.
Q 23A lack of molybdenum in soil causes whiptail, a disorder seen above all in which vegetable crop?
Cauliflower
Cauliflower is the classic victim, and the cure is simple: growers add lime to acid soil, which frees the molybdenum that was locked up in it.
Q 14Which country has long mined more molybdenum than any other and also holds the largest reserves?
China
China mined over 40 percent of the world's molybdenum in 2024, well ahead of South America and North America, the other two great producing regions.
Q 15Molybdenum-99 decays into which element, the workhorse of hospital nuclear medicine scans?
Technetium
Technetium made this way is used in tens of millions of scans a year, more than any other medical radioisotope. It fades within hours, so hospitals must make it fresh.
Q 16Molybdenum in type 316 stainless steel, used on boats, stops pitting by which everyday substance?
Salt
Salt in seawater pits ordinary stainless steel, so the version with 2 to 3 percent molybdenum became known as marine grade. Surgical steel comes from the same family.
Q 17Which legume, a New Year's good-luck dish in the US South, tops tables of molybdenum-rich foods?
Black-eyed peas
Black-eyed peas pack about 288 micrograms of molybdenum into half a cup, more than six times an adult's daily need.
Q 18Which Swedish chemist, an unlucky co-discoverer of oxygen, first identified molybdenum in 1778?
Carl Wilhelm Scheele
Carl Wilhelm Scheele showed that the mineral molybdena hid an unknown element but never isolated the metal himself. Another Swede, Peter Jacob Hjelm, did that three years later.
Q 19A 1976 Soviet probe brought back rock holding a microscopic grain of molybdenum from which world?
The Moon
The Moon sample came from Mare Crisium, the Sea of Crises, where Luna 24 drilled about two metres down. The molybdenum grain was roughly a thousandth of a millimetre long.
Q 20Slippery molybdenum disulfide turns up in greases, bullet coatings and which winter-sport product?
Ski wax
Ski wax can carry molybdenum disulfide because the compound's layers slide over one another, the same trick that keeps bearings moving when oil is lost.
Q 24Wulfenite, a molybdenum mineral prized for orange-red crystals, is which US state's official mineral?
Arizona
Arizona adopted wulfenite in 2017, and its Red Cloud Mine is one of the most noted sources of the thin, tabular crystals.
Q 25In which occupied country did Allied bombers twice raid the Knaben molybdenum mines during 1943?
Norway
Norway's Knaben mines were among the few in Europe still producing molybdenum, so British Mosquitoes struck in March and 130 American B-17s followed in November.
Q 26The first artificially made element was found in molybdenum foil taken from which kind of machine?
Cyclotron
Cyclotron inventor Ernest Lawrence posted the radioactive scrap from California to Sicily, where Emilio Segrè and Carlo Perrier proved in 1937 that it held element 43.
Q 27Which country's Chalk River reactor was long the world's biggest source of medical molybdenum-99?
Canada
Canada's NRU reactor made more medical isotopes than any other facility, so when it was shut down in late 2007 hospitals around the world ran short.
Q 28Molybdenum belongs to which small family of elements, defined by great resistance to heat and wear?
Refractory metals
Refractory metals number just five by the strictest count, and molybdenum is the most widely used of them, melting only at 2,623 °C.
Q 29Most medical molybdenum-99 is made in reactors by splitting atoms of which heavy element?
Uranium
Uranium-235 targets are bombarded with neutrons, and about six percent of the atoms that split leave molybdenum-99 behind. It loses half its strength every 66 hours.
Q 30Chromoly, a molybdenum steel loved by bike frame builders, is classic tubing for which race-car part?
Roll cage
Roll cage builders prize chromoly for its strength-to-weight ratio, and the same family of alloys is accepted for the barrels of the US military's M16 rifle.