Ammonium chloride is the result of the reaction of ammonia and hydrogen chloride
The name of the Russian armoured cruiser became well known during the October Revolution of 1917.
This animation demonstrates the components (vertices, edges, diagonals and faces) of the cube, one of the Platonic solids.
The cannon was an important type of firearms at the beginning of modern history, widespread both on land and water.
Medieval Venice owed its wealth to its flourishing maritime trade.
The city with advanced culture was the first settlement in history to have a citadel.
Large construction sites provide archaeologists searching for artefacts with a great deal of work.
An exercise about the regular hexahedron built from unit cubes to help deepen your knowledge of cubes.
Archimedes was one of the most brilliant Greek scholars of ancient times, who made his mark with military inventions as well.
The work of smiths – one of the first professions in history – became even more important in the Middle Ages.
Atmospherical nitrogen is bound by bacteria and used by living organisms in the form of various compounds.
The suspension bridge that stretches above the strait between San Francisco Bay and the Pacific Ocean was opened in 1937.
Karst formations include dolines and dripstones.
A mobile, nuclear-capable ballistic missile developed at the end of the Cold War.
Farming techniques evolved with the development of human civilisation in the Middle Ages and the Modern Age.
Common ciliated eucaryotic unicellular organisms widespread in freshwaters.
The Earth is divided into geographical and climatic zones, which result in the zonation of vegetation.
The boundaries of tectonic plates can be seen on the seafloor.
A glacier is a large body of ice that forms from snow, and is in constant, slow motion.
Submarines had an important role in naval warfare as early as World War I.