Beyond the answers - interesting background to this quiz

A coastline shared by a crowded neighbourhood

The Mediterranean is bordered by a striking number of countries and territories, which is why it has long served as one of the world's busiest crossroads for trade, migration and empire. Its northern shore takes in Spain, France, Italy and Greece, while its southern and eastern edges reach across North Africa and the Levant. That density of nations packed around a single sea helps explain why the region has produced so much shared history - and so many border disputes.

When a country changes its money

France's adoption of the euro in 2002 meant saying goodbye to the franc, a currency with centuries of history behind it. The shift was part of a wider move by European Union members to replace national currencies with a single one for everyday trade and travel. Mexico, by contrast, kept its own peso, a name that echoes the silver coins that once circulated across the Spanish-speaking world.

Silver, gold and the logic of chemical symbols

The symbol Ag for silver comes from the Latin argentum, which also gave us the name Argentina. Gold's symbol, Au, traces back to aurum, and both metals have been prized for thousands of years for their shine and resistance to corrosion. Learning a few of these Latin roots makes the periodic table far less arbitrary than it first appears.

La Paz and the thin air of high cities

La Paz sits high in the Bolivian Andes and is often described as the world's highest administrative capital, with the seat of government at extraordinary altitude. Visitors frequently notice the thin air, which can leave even short walks feeling strenuous. Its historic centre, steep streets and indigenous heritage make it one of South America's most distinctive cities.

A riddle older than chemistry

The puzzle about something that lives when fed and dies when given drink points to fire, one of the oldest subjects of human fascination. Fire needs fuel and oxygen, and water smothers it - a simple observation that ancient thinkers turned into riddles long before modern science explained combustion.