Explanation: Pure metals are soft and ductile, which is not ideal for most engineering applications. Therefore, alloys are used to fulfill the requirements. This explains why pure gold is mixed with impurities to make ornaments.

Explanation: Acetal is an example of engineering thermoplastics. These are the plastics that are typically employed in engineering applications due to high strength, environmental resistance, and physical properties. Other examples of engineering thermoplastics are ethenic, cellulose, polyether etc. Urethane, melamine, and epoxide are examples of engineering thermosetting plastics.

Explanation: Molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are common sulfide materials used in lubrication. Metalloid elements like germanium and silicon are used as electronic devices. Intermetallics like Nickel aluminide are used in water coatings.

Explanation: Fiberglass is known as the glass that has been drawn into fine fibers. They are inorganic in nature which makes them greatly inert. They also exhibit a high strength to weight ratio, non-flammability, and resistance to heat. For engineering applications, they are used for thermal and acoustic insulation, and as reinforcements for plastics.

Explanation: Compared to most metals and plastics, ceramics have a very good limit of maximum use temperature. It lies around 2760oC for ceramics, while metals and plastics lay lower at 815oC and 260oC respectively.

Explanation: Engineering ceramics have good tensile strength, compressive strength, hardness, and excellent creep resistance. Metals usually have gold creep resistance, but plastics fair poorly.

Explanation: Contents of alloys improve or decrease the hardness and strength of materials. Finer grain sizes improve the strength of the material. Imperfection and defects reduce the strength of the material. Shape, however, has little or no effect on the material.

Explanation: Since brittle materials are unsuitable for tension test, they are checked using a compressive test. Brittle materials such as cast iron, concrete, mortar, brick, and ceramics are commonly tested in compression.

Explanation: The temperature at which a substance changes from solid state to liquid is known as the melting point; here the temperatures of solid and liquid are in equilibrium. The shift of liquid state to solid is known as the freezing point. The transition from gaseous state to liquid is known as condensation, while that of liquid to gaseous is known as the boiling point.

Explanation: Since atomization results in oxidation of molten metal as it comes in contact with air, it is only used for materials like zinc and cadmium. Electrolysis is a standard electrolytic process which is used for materials like silver and tin. It is advantageous as it produces oxidation resistant powders.

Explanation: Seebeck, Peltier, and Thomson are three distinct effects which make up the thermoelectric effect. Ettingshausen effect, however, is a separate thermoelectric phenomenon like the Nernst effect.

Explanation: The Rockwell hardness F-scale uses a 1/16 inch diameter steel ball indenter with a total indenting load of 60 kg. This is used for testing of copper and brass.

Explanation: Alloy steels are used to improve properties such as strength, hardness, ductility, grain structure, and machinability, among others. This, however, results in increased costs due to multiple elements involved in the process.

Explanation: Similar to Brinell’s test, Vicker’s test also employs forcing of the indenter into the surface of metal for about 10-15 seconds. However, instead of a ball indenter, a pyramid-shaped indenter is used. This test is commonly also called the diamond-pyramid hardness test.

Explanation: Aluminum oxide (Al2O3) is regarded as the oldest engineering ceramic. They have excellent hardness and wear resistance. They are stiffer and stronger than steels. Their tensile and toughness properties, however, can be improved by mixing them with zirconium.

Explanation: Stainless steels contain iron and a minimum of 10.5% of chromium. This gives it great resistance to corrosion. Therefore, stainless steels are often known as corrosion-resistant steels or chromium-bearing steels.

Explanation: Silicon carbide has excellent tensile strength, oxidation resistance, and the highest thermal conductivity among the common engineering ceramics. However, it is expensive and only available in limited shapes and sizes. It also has a low strength.