is a yellow soft metal. It is most malleable and ductile of all the metals. One
gram of gold can be drawn into a wire of one and a half kilometre long. Gold is very nonreactive or inert metal. It is not affected by atmosphere. It is not even affected by any single mineral acid or base. Because of its inertness in atmosphere, it is an ornamental metal as well as used
in making coins. Gold is too soft to be used as such. It is always alloyed with copper, silver or some other metal.
Purity of gold is shown by carats that indicates the number of parts by weight of gold that is present in 24 parts of alloy. Twenty four carat gold is pure. 22 carats gold means that 22 parts pure gold is alloyed with 2 parts of either silver or copper for making ornaments and jewelry. White gold is its alloy with palladium, nickel or zinc.
Platinum is used to make jewelry items because of its unique characteristics like
colour, beauty, strength, flexibility and resistance to tarnish. It provides a secure setting for diamonds and other gemstones, enhancing their brilliance. An alloy of platinum, palladium and rhodium is used as catalyst in automobiles as catalytic converter. It converts most of the toxic gases (CO, NO 2) being emitted by
vehicles into less harmful carbon dioxide, nitrogen and water vapour. Platinum is used in the production of hard disk drive coatings and fibre optic
cables. Platinum is used in the manufacturing of fibre glass reinforced plastic and glass for liquid crystal displays (LCD).
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