Question

Identify the odd term out and explain: Gold, silver, copper, brass.

Answer 1

Alloys are metals made by combining two or more metals or a metal and a non-metal to improve strength and resistance to corrosion. For example, stainless steel and invar are two alloys of iron. Stainless steel is formed by alloying iron, nickel and chromium and invar is formed by alloying nickel and iron. On the other hand, pure metals are metals that have not been joined or combined with any other metal or metals. For example, aluminium, iron, nickel etc. are pure metals as they are not formed by combining two or more metals.

Complete step by step answer:
-The four given options are gold, silver, copper and brass. We need to figure out which one is the odd one out of these four.
-Let us first consider gold. Gold is a chemical element with the atomic number 79 and has the atomic symbol Au. It is a lustrous metal and is found to occur naturally on the earth. Gold is considered to be a precious metal which means it is a very rare and naturally occurring chemical element having very high economic value. The precious metals are found to be less chemically reactive than most other metals. Thus, gold is found to be one of the least reactive metals. Because of its malleability, ductility and shiny properties, gold is used in making jewellery and also in coinage.
-Next, we have silver. Silver is a chemical element with the atomic number 47 and has the atomic symbol Ag. Like gold, it is also a lustrous transition metal and is found in pure elemental form in the earth’s crust. Alongside gold, silver is also a precious metal. Thus, silver is also used in currency, jewellery and also in making utensils.
-Copper is a chemical element with the atomic number 29 and has the atomic symbol Cu. It is a soft, ductile and malleable metal with red-orange luster. It has very high thermal and electrical conductivity.
-On the other hand, brass is not a pure metal. It is an alloy made by combining the elements copper and zinc. It may also contain small proportions of various other elements. It has a gold-like appearance and hence it is used in decorations and also in jewellery and kitchenware.

Thus, brass is the odd one out as it is an alloy and the rest three are pure metals.

Note:
Alloying a parent metal with other metals results in properties which are superior to the parent metal. For example, the properties like strength, hardness, durability, tensile strength, toughness, ductility etc. are increased. For example, brass which is an alloy of copper and zinc, is harder than the parent metal copper. Bronze, which is an alloy of copper and tin, is hard and strong, has a shiny surface and doesn’t corrode easily. This is why bronze is used in making statues, medals and swords.