Beyond the answers - interesting background to this quiz

The Queen of Crime and her nursery rhyme murders

Agatha Christie wrote Five Little Pigs in 1942, and the title comes from the nursery rhyme about five little pigs going to market. The novel is one of her Hercule Poirot mysteries, and unusually for Christie, it turns on a murder that happened sixteen years earlier, reconstructed entirely through five witnesses' memories. Christie remains the best-selling novelist of all time, with sales estimated in the billions.

A capital that is not the biggest city

Washington, D.C. has been the capital of the United States since 1800, when the government moved there from Philadelphia. It is not part of any state, and it is far smaller than New York or Los Angeles. The city was planned specifically as a federal district, which is why it answers directly to Congress rather than to a state government.

France, the country with the most neighbours

Italy, Spain and Belgium all share a border with France, which has land borders with eight countries in total, more than any other European nation. That position has made France a crossroads of European trade, language and cuisine for centuries. Belgium's border with France runs for hundreds of kilometres, while Spain and Italy each meet France along the Pyrenees and the Alps respectively.

Einstein's Nobel Prize was not for relativity

Albert Einstein received the 1921 Nobel Prize in Physics, awarded in 1922, but not for his theory of relativity. The committee honoured him for his discovery of the law of the photoelectric effect, a piece of work that helped lay the foundations of quantum theory. Relativity was still considered too speculative at the time, a decision that remains one of the most discussed omissions in Nobel history.