Beyond the answers - interesting background to this quiz

One river, ten countries

The Danube is often called the world's most international river, and the description is hard to argue with. It rises in Germany's Black Forest and flows east for roughly 2,850 kilometres before emptying into the Black Sea. Along the way it passes through or borders ten countries, including Serbia, where it cuts through Belgrade. Vienna, Budapest and Bratislava are all Danube cities, which is why the river shows up so often in Central European history.

Why the Olympic rings look the way they do

The five interlocking rings were designed by Pierre de Coubertin, the founder of the modern Olympic movement, and unveiled in 1913. The colours - blue, yellow, black, green and red - were chosen so that at least one of them appears on the national flag of every country competing. The rings themselves represent the five inhabited continents, bound together by the Games.

A capital that speaks two languages

Brussels is more complicated than its tidy Grand-Place suggests. It is the capital of Belgium, but it is also officially bilingual, with French and Dutch sharing equal status in the city's institutions. On top of that, it hosts the main institutions of the European Union, which is why "Brussels" is often used as shorthand for EU decision-making. Antwerp and Bruges, the other two options, are both Flemish cities with their own distinct characters.

The chemistry of a single letter

Chemical symbols are usually easy to guess, but a few trip people up. H stands for hydrogen, the lightest element in the periodic table and the most abundant substance in the universe. Helium is He and holmium is Ho, which is why both are plausible distractors in a hurry. Hydrogen's symbol is also the reason it appears first in the periodic table, long before the heavier elements most of us remember from school.

Tapas and the art of eating late

Tapas are small plates served across Spain, often with a drink, and they are typically eaten in the early evening rather than as a formal dinner. The tradition is usually traced to bars serving a small snack, sometimes a slice of bread or ham, to accompany a glass of wine or beer. In many Spanish cities, dinner itself does not begin until well after 9 pm, which is why tapas fill the gap rather than replace the meal.