Beyond the answers - interesting background to this quiz

The invisible line that shapes a nation's identity

The equator crosses the territory of a dozen countries, and São Tomé and Príncipe is one of the smallest of them. This island nation sits in the Gulf of Guinea off the coast of West Africa, and the imaginary line passes through its southern island, São Tomé. Because of that position, the country enjoys a warm, humid tropical climate with little seasonal temperature variation. India and Australia, by contrast, lie entirely outside the equatorial band.

Sunshine, skin and a vitamin you make yourself

Vitamin D is unusual among nutrients because your body can produce it on its own, given enough sunlight. When ultraviolet B rays reach the skin, they trigger a reaction that converts a form of cholesterol into vitamin D. This is why the vitamin is often called the "sunshine vitamin". It plays a key role in helping the body absorb calcium, which matters for bone health. In darker winter months or at high latitudes, sunlight exposure can drop sharply.

A pencil born out of wartime shortage

Nicolas-Jacques Conté was a French painter, chemist and inventor who lived through the turbulent years of the French Revolution. In 1795, with graphite supplies scarce, he developed a method of mixing powdered graphite with clay, shaping the mixture into rods and firing them in a kiln. This technique allowed the hardness of the "lead" to be adjusted and made pencils far more practical to produce. His name still appears on drawing pencils sold today.

When a capital city is only a name

Mexico City and Panama City are both real, thriving capitals. "Nicaragua City" is not: Nicaragua's capital is Managua. The confusion is understandable, since many countries do have a capital that shares the national name. This kind of question is a reminder that place names follow no fixed rule. Some capitals, like Managua or Ottawa, carry entirely separate names from their countries.

Two letters, one element

Magnesium's chemical symbol is Mg, a nod to its Latin-derived name. The element is essential to life: it sits at the centre of the chlorophyll molecule, which plants use to capture light during photosynthesis. Humans need it too, for muscle and nerve function. Confusingly, Mn stands for manganese, a different metal entirely, which is why the two are easy to mix up.