Beyond the answers - interesting background to this quiz

A piano piece that helped define a city

George Gershwin composed "Rhapsody in Blue" in 1924, and it became one of the first works to blend classical concert music with jazz. The famous opening clarinet glissando was reportedly improvised in rehearsal by Ross Gorman and kept in the score. Gershwin later described the piece as a "musical kaleidoscope of America."

Buenos Aires and its rivalries

Buenos Aires is Argentina's capital and largest city, sitting on the Rio de la Plata. It is often compared to European capitals for its grand boulevards and café culture, shaped by waves of immigration in the late 19th and early 20th centuries. The city's name means "fair winds" in Spanish.

Hydrogen: the odd one out

Hydrogen sits at the top of the periodic table but is not a noble gas. Noble gases - helium, neon, argon, krypton, xenon and radon - occupy the far right column and are famously unreactive. Hydrogen, by contrast, is highly reactive and readily bonds with other elements, which is why it rarely appears alone in nature.

A planet with a pink glow

Mars is often called the Red Planet, but its sky can take on a pink or butterscotch hue. The colour comes from fine dust particles suspended in the thin atmosphere, which scatter light differently than Earth's air. Sunsets on Mars appear blue, the reverse of what we see here.

Mandela and the long road to the presidency

Nelson Mandela became South Africa's first democratically elected president in 1994, serving until 1999. Before that, he spent 27 years in prison for his opposition to apartheid. His release in 1990 and subsequent election are seen as turning points in the country's modern history.