Dissolution of NaCl

Common salt is dissolved by water: polar water molecules form a coat around the ions.

Sewage treatment plant

Treated sewage water can be used in agriculture and industry.

Neptune

Neptune is the outermost planet of the Solar System, the smallest of the giant planets

Open-cast mine

As opposed to underground mines, in open-pit mines the layers covering coal are removed, coal is extracted on the surface.

Cellulose (C₆H₁₀O₅)n

The building material of the cell walls and fibres of plants.

De Havilland DH-106 Comet 1 (1949)

The aircraft manufactured by the British de Haviland company was the world's first mass-produced commercial jetliner.

Measuring time

The first calendars and time-measuring instruments were already used by ancient Eastern civilisations.

Haemoglobin

Oxygen carrier protein in our red blood cells.

Leaning Tower of Pisa (14th century)

The medieval bell tower of the Cathedral of Pisa is the most famous leaning tower of the world.

Ictíneo II submarine

The submarine designed by the Spanish inventor Narcís Monturiol was a pioneering work in the history of underwater navigation.

Quinquereme (3rd century BC)

The warship having several rows of oars was the typical warship of the Hellenistic era.

Battle of Marathon (490 BC)

The marathon running event was instituted in commemoration of the run of a Greek soldier after the Battle of Marathon, fought between the Athenian and the...

Vision correction

Concave and convex lenses are used for the correction of short-sightedness and far-sightedness.

English battleship (18th century)

English sailing ships were among the best ships in the 17th-19th centuries.

Blitzkrieg strategy (1939-1940)

This effective strategy was based on the fast and synchronised attack of different branches of the army.

Non-orientable surfaces

The Möbius strip and the Klein bottle are special two-dimensional surfaces with only one side.

Stearic acid (octadecanoic acid) (C₁₇H₃₅COOH)

Solid, white substance, a constituent of vegetable oils and animal fats.

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