Beyond the answers - interesting background to this quiz

The spirit that travels under many flags

Vodka is most often associated with Russia and Poland, but it is distilled from whatever fermentable crop is cheap and plentiful locally. Potatoes, rye, wheat and even grapes all appear in different brands, which is why the base ingredient rarely tells you much about quality. The word itself comes from a Slavic term roughly meaning "little water".

Why Mercury looks so perfectly round

Mercury is the smallest planet in the Solar System and orbits closest to the Sun, where tidal forces from solar gravity are strongest. Those forces help pull the planet into an almost perfect sphere, leaving it with very little of the equatorial bulge that larger, faster-spinning worlds develop. Its heavily cratered surface, by contrast, is anything but smooth.

Athens and the revival of an ancient idea

The first modern Olympic Games opened in Athens in 1896, more than 1,500 years after the ancient Greek games were abandoned. Athletes from around a dozen nations competed in events that included athletics, cycling, fencing and swimming, with the marathon making its debut as a tribute to the legendary run from Marathon to Athens.

Two rivers, three capitals

Prague, the Czech capital, sits on the Vltava, the longest river in the country and the subject of one of Bedrich Smetana's best-known symphonic poems. Budapest, by comparison, is built along the Danube, while Belgrade lies at the meeting point of the Danube and the Sava. Rivers have shaped these cities' trade, defences and skylines for centuries.

Denpasar and the difference between a city and a capital

Denpasar is the largest city and administrative centre of Bali, yet Indonesia's capital is Jakarta, with a planned move to Nusantara under way. Doha and Dublin, by contrast, are both national capitals. The confusion is common: plenty of major cities, from Istanbul to Sydney, are not their country's seat of government.