Beyond the answers - interesting background to this quiz

The metal that got its name from a plant

Aluminium's symbol, Al, comes from alum, a family of mineral salts that people used for dyeing and tanning long before anyone isolated the metal itself. In 1808, Humphry Davy proposed the name "aluminum" for the element he believed was hidden inside those salts; later writers adjusted it to "aluminium" to match the -ium ending of most elements. Both versions are still in circulation today, though which one you see depends largely on where you live.

Mountains older than the Himalayas

The Western Ghats run for roughly 1,600 kilometres along India's western coast, and they are far older than the Himalayas. Their age and isolation have turned them into one of the world's great biodiversity hotspots, home to species found nowhere else on Earth. The range also acts as a climate barrier: it wrings heavy monsoon rain out of the clouds, which is why the coastal side is lush while the interior lies in rain shadow.

A desert nearly as big as a continent

Stretching across much of North Africa, the Sahara is the largest hot desert on the planet. It is not just sand, either: dunes, gravel plains, rocky plateaus and even mountain ranges all form part of its landscape. Its size has shifted dramatically over time - evidence suggests it has cycled between arid desert and green savannah as Earth's orbit and climate changed.

The boy in blue and the painter who struggled for years

Thomas Gainsborough painted "The Blue Boy" around 1770, and it remains one of the most recognisable portraits in British art. The subject is widely believed to be Jonathan Buttall, the son of a wealthy merchant and a friend of the artist. Gainsborough painted it partly to prove a point: he wanted to show that blue, a colour then considered difficult for portraits, could dominate a painting successfully. It now hangs in the Huntington Library in California.