The dissolution of zinc in hydrochloric acid produces hydrogen gas.
Mercury is innermost and smallest planet of the Solar System.
Saturn is the second largest planet in the Solar System, easily recognisable by its rings.
A glacier is a large body of ice that forms from snow, and is in constant, slow motion.
Jamestown, founded in 1607, was the first permanent English settlement on the east coast of North America.
The work of smiths – one of the first professions in history – became even more important in the Middle Ages.
Medieval Venice owed its wealth to its flourishing maritime trade.
The cannon was an important type of firearms at the beginning of modern history, widespread both on land and water.
These excellent shipbuilders and sailors travelled great distances on the seas and rivers.
A wide variety of torture devices were in use in medieval dungeons.
Typical working-class districts with unhealthy living conditions were built at the time of the Industrial Revolution.
The device designed to carry out executions more humanely than before was named after a French doctor.
The Olympic Games, held in the town every 4th year after 776 BC made it one of the centres of ancient Greece.
Hydrogen atoms within hydrogen molecules are held together by a covalent bond.
Fatty acid molecules consist of a polar head and a non-polar tail, therefore they are suitable for removing fat stains.
During the substitution reaction the hydrogen atoms of methane are substituted with chlorine atoms, the by-product is hydrogen chloride.
Limestone is a widely and diversely used material.
The topmost layer of our skin is the epidermis, which contains melanocytes.
Solar power stations convert solar energy into electricity.
Farming techniques evolved with the development of human civilisation in the Middle Ages and the Modern Age.