During the substitution reaction the hydrogen atoms of methane are substituted with chlorine atoms, the by-product is hydrogen chloride.
Fatty acid molecules consist of a polar head and a non-polar tail, therefore they are suitable for removing fat stains.
Hydrogen atoms within hydrogen molecules are held together by a covalent bond.
Static warfare was one of the characteristics of WWI
The device designed to carry out executions more humanely than before was named after a French doctor.
The ´Flying Fortress´ was developed for the United States Army Air Force by Boeing
The topmost layer of our skin is the epidermis, which contains melanocytes.
Jamestown, founded in 1607, was the first permanent English settlement on the east coast of North America.
Spitfire was a legendary British single-seat military aircraft used in World War II.
A mobile, nuclear-capable ballistic missile developed at the end of the Cold War.
Typical working-class districts with unhealthy living conditions were built at the time of the Industrial Revolution.
A wide variety of torture devices were in use in medieval dungeons.
These excellent shipbuilders and sailors travelled great distances on the seas and rivers.
The cannon was an important type of firearms at the beginning of modern history, widespread both on land and water.
Large construction sites provide archaeologists searching for artefacts with a great deal of work.
Medieval Venice owed its wealth to its flourishing maritime trade.
Atmospherical nitrogen is bound by bacteria and used by living organisms in the form of various compounds.
The work of smiths – one of the first professions in history – became even more important in the Middle Ages.
Ziggurats were typical terraced step pyramids used as temples in ancient Mesopotamia.
Farmhouses in the Middle Ages were simple, single-storey structures built from earth, mud and wood.