Beyond the answers - interesting background to this quiz

Why the hottest planet is not the closest one

Mercury sits closest to the Sun, yet Venus is the hotter of the two. The reason lies in Venus's thick atmosphere, which is dominated by carbon dioxide and laced with clouds of sulphuric acid. This blanket traps heat so effectively that surface temperatures reach around 465 degrees Celsius, hot enough to melt lead - and hotter than Mercury, which has almost no atmosphere to hold warmth in.

The symbol that comes from a Latin name

Potassium's chemical symbol is K, which looks odd until you trace it back to the element's Latin name, kalium. Many element symbols follow this pattern: sodium is Na from natrium, iron is Fe from ferrum, and gold is Au from aurum. The names were often fixed by early modern chemists working in Latin, so the symbols preserved a language that everyday English later dropped.

The river behind Victoria Falls

Victoria Falls sits on the Zambezi, the fourth-longest river in Africa, which winds through several countries before emptying into the Indian Ocean. Local people call the falls Mosi-oa-Tunya, meaning "the smoke that thunders," a reference to the spray visible from a distance. The falls are neither the world's highest nor its widest, but their combined height and width produce one of the largest sheets of falling water on Earth.

Uzbekistan and the heart of Central Asia

Uzbekistan lies in Central Asia, a region that also includes Kazakhstan, Kyrgyzstan, Tajikistan and Turkmenistan. It is one of only two doubly landlocked countries in the world, meaning every one of its neighbours is also landlocked. Cities such as Samarkand and Bukhara were major stops on the Silk Road, and their architecture still draws travellers today.

A country of islands and a capital by the sea

The Solomon Islands is a nation of hundreds of islands in the South Pacific, and its capital, Honiara, sits on the island of Guadalcanal. Honiara's name comes from a local language and the city grew around a harbour that became strategically important during the Second World War. Today it is the country's largest urban centre and its main port.