Beyond the answers - interesting background to this quiz

A mountain range that crosses an international border

The Appalachian Mountains are usually associated with the eastern United States, but the range does not stop there. Its northern section extends into Canada, specifically into Quebec and the Atlantic provinces, which is why the quiz answer is Canada. The Appalachians are among the oldest mountain ranges on Earth, and their rounded, weathered profile is a visible sign of that great age.

Ljubljana, a capital with a Roman past

Ljubljana is the capital of Slovenia, a small country at the crossroads of Central Europe and the Balkans. The city grew on the site of the Roman settlement of Emona, and Roman remains are still visible in the modern centre. Nearby, Lake Bled and the Julian Alps draw visitors who often pair a city break with a mountain trip.

Argentina's long list of neighbours

Argentina shares borders with Chile, Bolivia, Paraguay, Brazil and Uruguay, making it one of the more connected countries in South America. The Andes form a natural frontier with Chile along much of the west, while the Iguazu Falls sit where Argentina meets Brazil. This mix of landscapes helps explain why the country spans everything from subtropical jungle to Patagonian ice.

How penicillin changed medicine

Alexander Fleming discovered penicillin in 1928, when he noticed that a mould had killed bacteria in one of his culture dishes. It took years of work by other scientists, including Howard Florey and Ernst Chain, to turn that observation into a usable drug. When penicillin entered widespread use in the 1940s, it transformed the treatment of infections and opened the antibiotic era.