Beyond the answers - interesting background to this quiz

When a city changes its name

Paris was not always Paris. In Roman times the settlement on the Seine was known as Lutetia, a name that survived in French as Lutèce. The Parisii, a Gallic tribe, gave the city its modern name, and over the centuries the old Roman title faded into history books and crossword puzzles. Today Lutèce lingers mainly in literary and poetic references to the French capital.

A mountain range shared by many

The Caucasus Mountains stretch between the Black Sea and the Caspian Sea, and they are not confined to a single country. Russia claims the northern slopes, while Georgia, Armenia and Azerbaijan sit to the south. The range includes Mount Elbrus, the highest peak in Europe, which makes the region a genuine crossroads of geography and culture.

The sea that separates neighbours

The Aegean Sea lies between Greece and Turkey, dotted with thousands of islands. Its name is tied to Aegeus, a figure from Greek mythology, though the exact story varies by telling. For travellers, the Aegean is a map of ferry routes, ancient ruins and coastlines that have shaped Mediterranean trade for millennia.

An element named after a pioneer

Meitnerium, symbol Mt, honours Lise Meitner, the Austrian-Swedish physicist whose work helped explain nuclear fission. It is a synthetic element, meaning it does not occur naturally and must be created in a laboratory. Naming an element after her was a belated recognition of a scientist who was long overlooked by prize committees.

Why 4 breaks the prime rule

A prime number has exactly two factors: one and itself. The number 4 has three - 1, 2 and 4 - so it fails the test. Two and three, by contrast, are primes, with two being the only even prime. It is a small distinction, but it trips up plenty of people under time pressure.