Beyond the answers - interesting background to this quiz

The planet where the weather never calms down

Neptune is the farthest planet from the Sun, and it is also the windiest. Its atmosphere whips up supersonic storms that rank among the fastest winds measured anywhere in the solar system. Despite receiving only a tiny fraction of the sunlight Earth gets, the planet radiates more heat than it absorbs, and that internal energy is thought to help drive its violent weather.

A mountain that stands alone

Mount Kilimanjaro rises in north-eastern Tanzania and is the highest peak in Africa. It is a dormant volcano rather than part of a long mountain chain, which is why it appears to stand in isolation above the surrounding plains. Its summit sits in the "freezing" category of climate zones, so climbers pass through several distinct ecological bands on the way up, from farmland and rainforest to alpine desert and ice.

A fear that is not quite what it seems

Agoraphobia is often described as a fear of open spaces, but that label is a simplification. In clinical terms it centres on anxiety about situations that feel difficult to escape from or where help might not be available, which can include crowds, public transport and queues as much as wide open ground. The word itself comes from Greek roots meaning "fear of the marketplace".

One element, two countries

Mendelevium is a synthetic element that does not occur naturally in useful quantities and is produced in laboratories, atom by atom. Its symbol, Md, honours Dmitri Mendeleev, the Russian chemist who arranged the elements into the periodic table. Fittingly, the element sits among the actinides, the heavy, mostly artificial metals at the bottom of the table.

The border where three countries meet

Italy, France, Austria and Switzerland all share borders in the Alpine region, and there are points where several of them converge. Italy touches France, Switzerland and Austria; those three also meet each other, which is why Italy is the country the other three have in common. The area around Mont Blanc and the Alps is a patchwork of tunnels, passes and boundary markers that hikers can cross on foot.