Beyond the answers - interesting background to this quiz

A country built on water

Bangladesh sits on the Ganges-Brahmaputra delta, the largest river delta in the world, and its landscape is crisscrossed by hundreds of waterways. Estimates of the exact number of rivers vary widely depending on how a river is defined and whether seasonal channels are counted, which is why sources rarely agree on a single figure. What is certain is that these rivers shape agriculture, transport and daily life across the country.

The element that honours a physicist

Roentgenium, symbol Rg, is a synthetic element that does not occur in nature and must be created in a laboratory, atom by atom. It is named after Wilhelm Conrad Roentgen, the physicist who discovered X-rays in 1895 and received the first Nobel Prize in Physics in 1901. Like other superheavy elements, Roentgenium is highly unstable, and only tiny numbers of atoms have ever been produced.

Zebras and the horse family

Although a zebra's stripes make it look unlike any domestic animal, it belongs to the genus Equus, the same group as horses and donkeys. The three living zebra species - plains, mountain and Grevy's - are all native to Africa. Stripes differ in pattern between species and even between individuals, and researchers continue to debate exactly what evolutionary pressures produced them.

A twelve-second leap into a new century

The Wright brothers' first powered flight took place on 17 December 1903 at Kitty Hawk, North Carolina, putting it firmly in the 20th century. Orville Wright was at the controls for the first attempt, which lasted about twelve seconds and covered roughly 36 metres. The brothers made four flights that day, the longest covering about 260 metres.

A scale that measures what, exactly?

The Richter scale, developed by Charles Richter in the 1930s, was designed to express the size of an earthquake using seismograph recordings. It is a logarithmic scale, meaning each whole number represents a roughly tenfold increase in measured amplitude. Modern seismology has largely replaced it with the moment magnitude scale, which gives more reliable results for very large earthquakes.