A colorless, odorless, non-reactive gas, it constitutes 78.1% of Earth´s atmosphere.
A compound ion produced from carbonic acid by releasing protons.
A colorless, odorless gas, an important component of the atmosphere, indispensable to sustain terrestrial life.
Colourless, odourless gas, highly toxic to humans and animals in high concentration.
Colourless, odourless, heavier-than-air gas. Necessary for the photosynthesis of plants.
The castle of Eger got its final shape and became an important component in the new chain of border forts in the 16th century.
Market towns became the most common type of towns in the Kingdom of Hungary by the Late Middle Ages.
Burj Al Arab, the world's only seven-star luxury hotel is located in the United Arab Emirates.
Crystalline allotrope of elemental carbon, the hardest known natural substance.
The small passenger aircraft is designed for speed, convenience and economical operation.
The iron lattice tower, erected for the 1889 World Fair, became the symbol of the capital city of France.
A floatplane (sometimes called hydroplane) is an aircraft capable of taking off not only dry land, but water too.
Rotating a rectangle around its axes of symmetry or around its sides results in solids of revolution.
This animation demonstrates several types of prisms, from general to regular.
The most popular European-made transport aircraft before World War II.
An exercise about the volume and surface area of solids generated from a ´base cube´.
A Zeppelin is a type of controllable, rigid airship.
This animation demonstrates various groups of solids through examples.
Viruses consist of protein and DNA or RNA; they reprogram infected cells to produce more viruses.
A colourful and entertaining animation to practise orientation in space.
Direct action pumps and suction pumps are among the simplest water pumps.