Beyond the answers - interesting background to this quiz

Why so many countries keep more than one capital

Dodoma became Tanzania's official capital in 1974, replacing Dar es Salaam, yet many government offices still operate in the older coastal city. A similar split exists in other countries: South Africa spreads its functions across Pretoria, Cape Town and Bloemfontein, while Bolivia has Sucre as its constitutional capital and La Paz as the seat of government. Moving a capital is rarely just a bureaucratic decision - it often reflects an attempt to shift political weight inland or spread development beyond a crowded coastal hub.

The printing press and the world it broke open

Johannes Gutenberg's movable-type press in mid-15th-century Germany did not invent printing from scratch - woodblock printing had existed in East Asia for centuries - but it made reproduction fast and affordable in Europe. Within decades, books that once took months to copy by hand were being produced in large numbers, and ideas travelled faster than any authority could control. It is hard to imagine the Reformation, the Scientific Revolution or mass literacy without it.

The quiet reach of magnetism

Iron's strong attraction to magnets comes down to its atomic structure, which allows tiny magnetic regions inside the metal to line up and reinforce one another. Aluminium can be affected by magnetism too, but only weakly, and nitrogen is not magnetic in any practical sense. This simple property underpins electric motors, generators, hard drives and MRI scanners - technologies that would be unthinkable if only a handful of metals behaved this way.

A lake shared by four nations

Lake Tanganyika stretches along the western edge of East Africa and is divided between Tanzania, the Democratic Republic of the Congo, Burundi and Zambia. It is one of the deepest lakes on Earth and holds a remarkable share of the planet's fresh water. Its isolation over millions of years has produced hundreds of fish species found nowhere else, making it a natural laboratory for anyone studying how species evolve.