Chemistry Test - 20

In mining, gangue is the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. The separation of mineral from gangue is known as mineral processing.

Highly reactive metals are extracted by the electrolysis of their molten chlorides or oxides.

For example, when molten sodium chloride is electrolysed, sodium metal is obtained on cathode and chlorine gas is obtained at anode.

Thermite is a pyrotechnic composition of metal powder and metal oxide that produces an exothermic oxidation-reduction reaction known as a thermite reaction. The most commonly used mixture is of iron oxide and aluminium.

Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered as a mixture of metal oxides and silicon dioxide. So, CaSiO₃ is known as slag.

Carbonate ores are converted into oxides through the process of calcination.

Electronic configuration of halogens is ns²np⁵, while hydrogen has half-filled valence shell, i.e. ns1.

Hydrogen and halogens both have a high ionisation energy.

Hydrogen can exhibit -1 oxidation state like the halogens.

Hydrogen as well as halogens occur as diatomic molecules.

Chalcophile elements concentrate in sulfides, such as Se, As, Zn, Cd.

Photochemical smog can be suppressed by certain compounds, which act as free radical traps and also by installation of efficient catalytic converters in automobiles.

Aquarium is an example of man made ecosystem.

Air is not a part of the biotic environment.