Beyond the answers - interesting background to this quiz

The coloured ring that gives every eye its identity

The iris is the pigmented ring around the pupil, and its colour comes from melanin, the same pigment that colours skin and hair. Brown eyes contain a lot of melanin, while blue eyes contain very little, which is why they scatter light in a way that looks blue. The sclera, by contrast, is the white outer coat of the eyeball, and the vitreous body is the clear gel filling the space behind the lens.

Hydrogen and the trouble with naming elements

Hydrogen takes its name from Greek words meaning "water-former", because burning it produces water. Its symbol is H, while Hg stands for mercury - a metal whose Latin name, hydrargyrum, also means "liquid silver". He, meanwhile, belongs to helium, the light gas discovered in the Sun's spectrum before it was found on Earth.

Yamato, Goryeo and Siam: names that outlived empires

Yamato was an early name for Japan, tied to a region and a ruling court that helped shape the country's early statehood. The other options in this quiz belong elsewhere: Goryeo gave Korea its modern name, and Siam was the former name of Thailand. Such old names often survive in poetry, brand names and historical writing long after maps have changed.

Aconcagua and the roof of the Americas

Aconcagua, in Argentina, is the highest peak in the Americas, rising close to the Chilean border in the Andes. It is also the highest mountain outside Asia, which makes it a serious goal for experienced climbers. Unlike Everest, Aconcagua involves no technical climbing on its standard route, but altitude and weather remain formidable obstacles.

Thomas Hardy's fictional Wessex

Thomas Hardy set The Mayor of Casterbridge in and around the market town of Dorchester, which he renamed Casterbridge in his fictional Wessex. The novel follows Michael Henchard, whose life unravels after a rash act at a country fair. Virginia Woolf and George Eliot were near contemporaries in the literary landscape, but the story of Henchard belongs firmly to Hardy's imagination.