Beyond the answers - interesting background to this quiz

How centuries get their names

It surprises many people that the 20th century runs from 1901 to 2000, not from 1900. The reason is that there was no year zero in the calendar most of the world uses: the 1st century began in the year 1 and ran to 100, so every century after it starts on a year ending in 01. The same logic means the 21st century only began on 1 January 2001.

The sailfish and its remarkable speed

The sailfish earns its reputation as the fastest fish in the ocean thanks to a distinctive, sail-like dorsal fin and a streamlined body built for short bursts of speed. Estimates of its top speed vary widely, but it is generally ranked ahead of other fast pelagic hunters such as marlin and tuna. It uses that speed to herd schools of smaller fish before striking.

Tin and the puzzle of chemical symbols

Tin's symbol, Sn, comes from stannum, the Latin name for the metal, which is why the symbol does not match the English word at all. This pattern appears throughout the periodic table: Sb for antimony comes from stibium, and Si belongs to silicon rather than tin. The mismatch is a reminder that chemistry's shorthand grew out of older, often Latin, terminology.

Baghdad and the Sahel: two very different geographies

Baghdad, the capital of Iraq, sits on the Tigris River and was founded in the 8th century, later becoming a celebrated centre of learning during the Islamic Golden Age. The Sahel is a different kind of place entirely: a semi-arid belt stretching across Africa just south of the Sahara, running through countries such as Niger, Mali and Chad. It marks a transition zone between desert and savanna.

A ballet that sparked a riot

Igor Stravinsky composed The Firebird for the Ballets Russes, and its 1910 premiere in Paris made his name. Three years later, the same partnership produced The Rite of Spring, whose premiere famously provoked a riot in the theatre. Stravinsky's rhythmic, harmonically bold style went on to influence composers across the 20th century.