General Science Quiz: Metals and Non-Metals

Calamine is zinc carbonate, and since it is a carbonate ore it is converted to the oxide by calcination, that is by heating in the absence of air, before being reduced to the metal.

Silver is an element, a pure metal with its own place in the periodic table, so it cannot be an alloy; an alloy is a homogeneous mixture of two or more metals, or of a metal with a non-metal such as carbon.

Ductility is the property of being drawn into a wire, and gold is the most ductile metal known; it is also the most malleable, so a very small quantity can be beaten into an extremely thin sheet or drawn into a very long wire.

Brass takes the workability of copper and the hardness of zinc, resists corrosion and is easy to cast, which is why it is used for utensils, locks, taps, fittings and wind instruments.

Mercury is the only metal that is liquid at ordinary room temperature, which is why it was long used in thermometers and barometers; it is also the metal that forms amalgams, alloys in which mercury is one component.

Aqua regia is three parts concentrated hydrochloric acid to one part concentrated nitric acid, and the name means royal water, given because the mixture attacks the noble metals gold and platinum, which neither acid can dissolve on its own.

Silver has the highest electrical conductivity of all metals and also the highest thermal conductivity, but it is costly and tarnishes, so it is used only in specialised contacts and instruments.

Galena is lead sulphide, the principal ore from which lead is obtained; being a sulphide it is concentrated by froth flotation and then roasted in air to the oxide before reduction.

In galvanisation iron or steel is given a coating of zinc, usually by dipping it in the molten metal, and the coating protects the iron in two ways: it keeps out air and moisture, and because zinc is more reactive than iron it corrodes in place of the iron even…

An amphoteric oxide reacts with both acids and bases to form salts, and aluminium oxide does exactly that, behaving as a base towards hydrochloric acid and as an acid towards sodium hydroxide; zinc oxide is the other amphoteric oxide asked in examinations.

Graphite is an allotrope of carbon in which each atom is bonded to three others, leaving one electron per atom free to move through the layers, so it conducts electricity although it is a non-metal; this is why graphite is used for electrodes and in dry cells.