Rubidium
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40 free Rubidium trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Rubidium is one of the least famous metals in the periodic table and one of the most dramatic. Element 37 is soft, silvery and so reactive that it must be sealed away from air and water, yet it quietly helps run satellite navigation, hospital imaging and some of the coldest experiments ever performed. This quiz turns the best rubidium fun facts into multiple-choice questions: how the element was discovered and named, how it behaves, where it is found in nature, and the surprising jobs it does in timekeeping, medicine and research. Every answer comes with a short explanation, so you get the story behind each fact. It suits chemistry students revising the periodic table, teachers who want an element-of-the-week activity, and anyone who likes a good science fact to share.
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Q 01Rubidium was named by its discoverers for which color of the bright lines in the light it emits?
Red
Red is the answer: the name comes from rubidus, meaning deep red, after bright lines in its spectrum that matched no known element.
Q 02Rubidium metal melts at about 39 °C, only a couple of degrees warmer than which of these?
The human body
The human body runs at about 37 °C, which makes rubidium one of only five metals that are liquid at or near room temperature, alongside mercury and gallium.
Q 03Which element sits immediately before rubidium, element number 37, in the periodic table?
Krypton
Krypton shares its name with Superman's home planet, and radioactive rubidium-82 decays into it within minutes.
Q 04Rubidium sounds rare, yet it is more abundant in Earth's crust than which of these everyday metals?
Copper
Copper is scarcer in the crust than rubidium, which only seems rare because it never gathers into rich ores of its own.
Q 05Doctors inject short-lived radioactive rubidium-82 to picture how well blood is reaching which organ?
Heart
The heart muscle soaks up rubidium-82 in step with its blood supply, and with a half-life of barely over a minute the tracer must be made beside the patient.
Q 06Radioactive rubidium-87 has a half-life more than three times the 13.8-billion-year age of what?
The universe
The universe is about 13.8 billion years old, while rubidium-87 needs roughly 49 billion years to half decay, which is why about 28% of natural rubidium is still radioactive.
Q 07Which German chemist co-discovered rubidium by studying the colors that chemicals give to a flame?
Robert Bunsen
Robert Bunsen spotted rubidium in the light of a flame; his dangerous earlier work on arsenic compounds had cost him the sight in his right eye.
Q 08Rubidium reacts so violently with water that the reaction can ignite which gas it releases?
Hydrogen
Hydrogen is released so fast that shock waves form in the water, and rubidium, denser than its lighter relatives, sinks as it reacts.
Q 09NASA's Cold Atom Laboratory has chilled rubidium atoms into an ultracold cloud while orbiting aboard what?
A space station
A space station is the ideal home: in the endless free fall of the International Space Station, the rubidium cloud could be watched for more than a second.
Q 10A natural vibration in rubidium, about 6.8 billion cycles a second, regulates which devices aboard GPS satellites?
Atomic clocks
Atomic clocks based on rubidium are the cheapest, smallest and most widely made kind, keeping time for navigation signals far above the Earth.
Q 11Living cells absorb rubidium ions because they mistake them for which essential nutrient element?
Potassium
Potassium and rubidium ions carry the same charge and behave alike, so cells pull both in, although rubidium is not known to be a nutrient for any living thing.
Q 12Biology labs treat living cells with rubidium chloride to make them take up which molecule?
DNA
DNA slips in after the salt treatment makes the cells swell, the best-known job of rubidium chloride, probably the most used rubidium compound.
Q 13Rubidium nitrate is sometimes added to fireworks to give the bursts which color?
Purple
Purple, or a pale mauve, is what rubidium salts show in a laboratory flame test, the same trick that fireworks makers borrow.
Q 21Rubidium was first detected in which lilac-colored mica, of which its discoverers processed 150 kg?
Lepidolite
Lepidolite owes its pink tints to traces of manganese, and it is still mined today as a source of rubidium.
Q 22Rubidium was the second element discovered by its spectral lines, shortly after which other soft metal?
Caesium
Caesium came first, in 1860, when the same two scientists evaporated 44,000 litres of mineral water to collect a few grams of its salts.
Q 23When an atom of radioactive rubidium-87 decays, it becomes a stable atom of which neighboring element?
Strontium
Strontium is the next element along: each decay turns a neutron into a proton, nudging rubidium one place up the periodic table.
Q 14Which two-letter symbol stands for rubidium, element number 37, on the periodic table?
Rb
Rb is rubidium; the lookalike symbols Ru, Rh and Ra belong to ruthenium, rhodium and radium.
Q 15Rubidium belongs to which family of soft, highly reactive elements found in group 1 of the periodic table?
Alkali metals
Alkali metals each have a single outer electron that they give up easily, which is why rubidium is never found as a pure metal in nature.
Q 16To keep it safe and pure, rubidium metal is usually stored submerged in which dry liquid?
Mineral oil
Mineral oil keeps moisture away, and the alternative is a sealed ampoule of inert gas; even so, traces of air seeping into the oil slowly form peroxides.
Q 17Cooling rubidium atoms into a new state of matter in 1995 earned Eric Cornell and Carl Wieman which honor?
Nobel Prize in Physics
Nobel Prize in Physics went to both men in 2001, shared with Wolfgang Ketterle, who made the same state of matter later that year using sodium.
Q 18Rubidium is so reactive that a fresh piece exposed to open air has been reported to do what?
Catch fire
Catch fire is right: rubidium can ignite spontaneously in air, a trait chemists call pyrophoric, so samples are handled only under inert gas.
Q 19Which German physicist, known for his laws of electrical circuits, co-discovered rubidium with a chemist colleague?
Gustav Kirchhoff
Gustav Kirchhoff also read the Sun's light the same way, showing in 1859 that it contains sodium, two years before rubidium turned up.
Q 20Rubidium was first identified in a laboratory in which German city, home to the country's oldest university?
Heidelberg
Heidelberg drew both discoverers to its university in the 1850s; founded in 1386, it is the oldest in Germany.
Q 24In 1995, physicists chilled a cloud of rubidium-87 atoms to near absolute zero and created the first what?
Bose–Einstein condensate
A Bose–Einstein condensate makes separate atoms behave as one; predicted in the 1920s, this first one held only about two thousand of them.
Q 25Eric Cornell and Carl Wieman made rubidium atoms behave as one super-atom in a laboratory in which Colorado city?
Boulder
Boulder hosts JILA, the joint university and government institute where the pair cooled their rubidium to 170 billionths of a degree above absolute zero.
Q 26Rubidium chloride has been tested on volunteers as a possible treatment for which condition?
Depression
Depression was the target: volunteers took up to 720 mg a day for 60 days, but rubidium chloride never became a standard treatment.
Q 27Rubidium silver iodide, the best ion-conducting crystal known at room temperature, has been used in which devices?
Batteries
Batteries can use it as a solid electrolyte: silver ions slip through the crystal's framework so freely that no liquid is needed.
Q 28Scientists measure the slow decay of rubidium-87, which takes billions of years, to find the age of what?
Rocks
Rocks from Earth, the Moon and meteorites have all been dated this way, by weighing how much rubidium-87 has turned into its decay product.
Q 29Rubidium carbonate is added to which material to toughen it for fiber optics and night-vision devices?
Glass
Glass gains stability and durability from the additive while conducting less electricity, one of the few industrial jobs rubidium has.
Q 30Cheap, compact rubidium oscillators keep signals precisely timed inside which everyday network equipment?
Mobile phone towers
Mobile phone towers rely on them to hold their radio frequencies steady, and television transmitters use the same rubidium references.