The German liquid-propellant rocket, developed during WWII, was the first known man-made object to reach space.
Limestone is a widely and diversely used material.
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.
Spitfire was a legendary British single-seat military aircraft used in World War II.
Ziggurats were typical terraced step pyramids used as temples in ancient Mesopotamia.
A mobile, nuclear-capable ballistic missile developed at the end of the Cold War.
The device designed to carry out executions more humanely than before was named after a French doctor.
Jamestown, founded in 1607, was the first permanent English settlement on the east coast of North America.
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.
Large construction sites provide archaeologists searching for artefacts with a great deal of work.
Atmospherical nitrogen is bound by bacteria and used by living organisms in the form of various compounds.
Karst formations include dolines and dripstones.
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.
The Earth is divided into geographical and climatic zones, which result in the zonation of vegetation.
The topmost layer of our skin is the epidermis, which contains melanocytes.
Farmhouses in the Middle Ages were simple, single-storey structures built from earth, mud and wood.