Rhodium
0Loading crowd target
0Loading crowd target
6correct to beat the crowd
40 free Rhodium trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Rhodium is the precious metal most people have never heard of, even though many of them drive around with a little of it under the car. It is rarer than platinum, has at times cost many times more, and almost never appears as a solid object: it works in thin coatings and tiny specks of catalyst. This quiz collects the best fun facts about rhodium: the secretive chemist who discovered it, how it got its name, where on Earth it is dug up, and why thieves crawl under parked cars to get it. There are questions on its place in the periodic table, its jobs in jewellery, medicine and heavy industry, and a famous musician's unusual trophy. The questions run from easy to tricky, so they suit curious beginners, chemistry students and quiz fans alike. Every answer comes with a short explanation.
30 of 40 questions with answers and explanations. Play the quiz
Q 01Which former Beatle received a rhodium-plated disc from Guinness in 1979 as history's best-selling songwriter?
Paul McCartney
Paul McCartney was handed rhodium because ordinary record-industry award discs no longer matched his sales. The metal was picked as something rarer than platinum.
Q 02Rhodium takes its name from the Greek word for which flower, after the colour of its dissolved salts?
Rose
Rose is 'rhodon' in Greek, and the name suited the pinkish-red crystals the element's discoverer coaxed out of platinum ore. The pure metal has no such tint.
Q 03Thieves hunting rhodium most often saw the catalytic converters off which hybrid car, a pioneer of its kind?
Toyota Prius
Toyota Prius converters carry extra precious metal because a hybrid's engine runs less often and its exhaust stays cooler. More catalyst is needed to do the same cleaning job.
Q 04Which country mines about three-quarters of the world's rhodium, mostly from its vast Bushveld Complex?
South Africa
South Africa holds about 90% of the world's known reserves of platinum-family metals, packed into two rock layers that miners call reefs.
Q 05Jewellers routinely coat which metal, popular for engagement rings, with a thin layer of rhodium that slowly wears away?
White gold
White gold is naturally rather dull, so the rhodium supplies the bright shine buyers expect, a match for platinum. Some higher-quality alloys keep their lustre without it.
Q 06Rhodium is among the rarest elements in Earth's crust, yet traces have been measured in which staple vegetable?
Potatoes
Potatoes tested for the metal held between 0.8 and 30 parts per trillion. The crust itself averages less than one part per billion.
Q 07Which Swedish company introduced the three-way catalytic converter in 1976, sending demand for rhodium soaring?
Volvo
Volvo fitted the device first to its 240 model. Earlier converters, built on platinum or palladium, handled only two of the three main exhaust pollutants.
Q 08Rhodium catalysts helped industry turn methanol into acetic acid, the sour ingredient of which kitchen staple?
Vinegar
Vinegar has been made for thousands of years, which probably makes acetic acid the first acid ever produced in large amounts.
Q 09A rhodium catalyst, part of a process devised by Japan's Ryoji Noyori, makes which cooling flavour for chewing gum?
Menthol
Menthol comes naturally from mint plants, but a single Japanese firm makes about 3,000 tonnes of it a year this synthetic way.
Q 10Cars whose catalytic converters contain rhodium must avoid fuel laced with which metal, which ruins the catalyst?
Lead
Lead was added to petrol for decades to stop engines knocking, so the spread of converters forced the switch to unleaded fuel.
Q 11Which symbol stands for rhodium on the periodic table, where it sits at atomic number 45, just before palladium?
Rh
Rh also labels a blood-group factor, but there is no link: that name is short for rhesus, after the monkeys used in the original research.
Q 12Rhodium sits directly below which metal, famous for its deep blue pigments, in group 9 of the periodic table?
Cobalt
Cobalt once did rhodium's job in making acetic acid, until a rhodium catalyst discovered in the late 1960s proved able to work at lower pressure with almost no waste.
Q 13Rhodium detectors inside nuclear reactors, including Arizona's Palo Verde plant, track the flow of which particles?
Neutrons
Neutrons are tracked at Palo Verde by 305 rhodium detectors in each reactor, stacked on five levels to give a 3D picture of how the fuel is burning.
Q 21Which chemist discovered both rhodium and palladium while secretly refining platinum for profit in the early 1800s?
William Wollaston
William Wollaston hid the palladium discovery at first, selling the metal anonymously through a shop, and only owned up after he had found rhodium too.
Q 22Rhodium's discoverer gave up which profession in 1800, a few years before isolating the metal, to pursue chemistry?
Physician
Physician was a role that tormented him: worry over one patient reduced him to tears, and he wrote that losing thousands of pounds would hurt less than the anxiety.
Q 23Rhodium's discoverer began by dissolving crude platinum ore in which fuming acid mixture, long prized by alchemists?
Aqua regia
Q 14Which metal, abundant in the clay left by the dinosaur-killing asteroid, sits directly below rhodium in group 9?
Iridium
Iridium has largely taken over one of rhodium's old industrial jobs, turning methanol into acetic acid, because it does the same conversion more efficiently.
Q 15Rhodium was first isolated in a private laboratory in which capital city, where its discoverer had moved in 1797?
London
London was where the discoverer set up a laboratory behind his house in 1801 and guarded its privacy to the utmost. A secret platinum process worked out there made his fortune.
Q 16Rhodium's discoverer was also the first person to notice dark lines crossing the spectrum of which celestial body?
The Sun
The Sun's spectrum showed him the gaps twelve years before Joseph von Fraunhofer, whose name they now carry. He took them for mere boundaries between the colours.
Q 17A rhodium coating protects which jewellery metal from the black tarnish caused by sulfur compounds in the air?
Silver
Silver slowly blackens as sulfur in the air turns its surface into a dark sulfide. Rhodium never reacts that way, so a thin skin of it keeps sterling pieces bright.
Q 18Inside a three-way catalytic converter, rhodium's main job is to break down which family of smog-forming gases?
Nitrogen oxides
Nitrogen oxides are split by the rhodium into harmless gases that already make up the air we breathe. Platinum and palladium deal with the other exhaust pollutants.
Q 19The first cars with rhodium-bearing three-way catalytic converters were 1977 models built for sale in which US state?
California
California got the system three years before the same cars sold in the other 49 states, because its own smog rules demanded it.
Q 20A rhodium catalyst let industry mass-produce L-DOPA, a drug for which illness, earning its inventor a 2001 Nobel?
Parkinson's disease
Parkinson's disease is treated with L-DOPA because the body turns the drug into dopamine. The catalyst was designed to make only the useful mirror-image form of the molecule.
Aqua regia, a blend of nitric and hydrochloric acids, barely touches solid rhodium itself, a stubbornness later used to separate the metal from platinum.
Q 24Rhodium's discoverer patented which optical drawing aid in 1806, letting artists trace a scene onto paper?
Camera lucida
Camera lucida was his own coinage, Latin for a well-lit room, chosen as the opposite of the older camera obscura, or dark room.
Q 25Rhodium is among the most valuable precious metals; in 2021 one troy ounce peaked at close to how many US dollars?
$30,000
$30,000 an ounce was more than forty times what the same metal had fetched five years earlier, when it sold for under $700.
Q 26Natural rhodium is one of just 26 elements with only a single stable what, giving every atom the same mass?
Isotope
Isotope number 103 is the only form of rhodium found in nature. Dozens of radioactive versions have been made in laboratories, most of them lasting less than an hour.
Q 27Rhodium forms inside nuclear reactors as a fission product when atoms of which fuel element split apart?
Uranium
Uranium fission leaves rhodium in spent fuel, but nobody extracts it on a large scale: the radioactive waste would first have to cool for about ten years.
Q 28Rhodium's discoverer and his partner bought the smuggled platinum ore that yielded it on which festive date in 1800?
Christmas Eve
Christmas Eve 1800 brought a purchase that yielded four new elements: the two partners divided the work, and each found a pair of them in the same batch of ore.
Q 29Which American company, later famous for Roundup weedkiller, built the first plant using rhodium to make acetic acid?
Monsanto
Monsanto opened the plant in 1970, and its rhodium method went on to become the dominant way of making the acid worldwide.
Q 30At Sudbury in Canada, rhodium is a by-product of mining which metal, a key ingredient of stainless steel?
Nickel
Nickel ore at Sudbury holds only a trace of rhodium, but so much rock is processed there that recovering the precious metal still pays.