Beyond the answers - interesting background to this quiz

A line that outgrew its story

"You know nothing, Jon Snow" is spoken by Ygritte, the wildling woman Jon Snow meets beyond the Wall in George R. R. Martin's A Song of Ice and Fire and in Game of Thrones. The phrase became one of the most quoted lines of the series, and later a popular internet meme. It works because it is both teasing and affectionate, and because Jon, for all his honour, really does misunderstand the world he has entered.

The Caucasus, a crossroads of three nations

Armenia, Azerbaijan and Georgia lie south of the Caucasus Mountains, the range that separates them from Russia to the north. The region sits at the boundary between Europe and Asia, which is one reason its borders and identities have been contested for centuries. It is also strikingly diverse: the three countries have different languages, alphabets and religious traditions, and each has its own long history of statehood.

The Mona Lisa's long, slow creation

Leonardo da Vinci painted the Mona Lisa in the 16th century, and most scholars believe he worked on it over several years rather than finishing it quickly. He is thought to have carried it with him for much of his later life, refining details such as the famous soft edges of the face. Today it hangs in the Louvre in Paris, where it draws enormous crowds and is protected behind glass.

Plucking, not bowing

Pizzicato is the technique of plucking the strings of an instrument instead of drawing a bow across them, and it is standard on the cello. Composers use it for short, crisp effects, and entire passages can be played this way. The word comes from the Italian pizzicare, meaning to pinch or pluck, which is exactly what the player's fingers do.

A gas with a surprising history

Nitrous oxide is known as laughing gas because inhaling small amounts can produce giggles, light-headedness and a sense of euphoria. It was first prepared in the 18th century, and public demonstrations of its effects became popular entertainment before it found medical use. Today it is widely used in dentistry and surgery as a mild anaesthetic and painkiller.