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The correct choice is (a) Epoxies

The EXPLANATION: Epon, Durcon, and Araldite belong to epoxies. These materials are the best combination of corrosion RESISTANCE and mechanical properties. It is mainly used as PROTECTIVE coatings, LININGS, and ADHESIVES.

Right option is (B) Silicon CARBIDE, alumina, and zirconia

For explanation: MUCH research is ongoing to produce ultra-tough ceramics such as silicon carbide, silicon nitride, alumina, and zirconia. This research aims to reduce the brittleness such that these materials could be used in DIESEL engines and gas TURBINES.

Correct choice is (c) Magnesium

To ELABORATE: Magnesium is ONE of the lightest commercial metal with specific gravity 1.74. It is utilized in trucks, automobile engines, aircraft, and MISSILES. Whereas METALS such as stainless steel, carbon STEELS, and cast irons are regarded as heavy metals.

Right ANSWER is (c) Both metallic and non-metallic elements

For explanation I WOULD say: Ceramics are the other class of non-metallics. It usually consists of metallic and non-metallic elements.Magnesia, PORCELAIN is the BEST examples of ceramics.

The correct option is (c) Both phenol and formaldehyde

For EXPLANATION: Bakelite is one of the most widely used thermosetting plastics for various DOMESTIC and industrial APPLICATIONS. Phenol or CARBOLIC acid and formaldehyde are the raw MATERIALS of Bakelite.

The correct option is (c) It has good THERMAL and electrical CONDUCTIVITY, excellent thermal shock resistance, weak and brittle as compared with METALS

For explanation: Carbon and graphite are the unique non-metallics that are good thermal and electrical conductors with excellent thermal shock resistance. They are weak and brittle as compared with metals.

Correct answer is (c) Teflon

Best explanation: Teflon is ONE of the FLUOROCARBONS which is REGARDED as noble metals of plastics. It is corrosion-resistant to practically all environments up to 550°F. The MONOMER of Teflon is denoted as CF2=CF2.

The CORRECT answer is (b) Inconel

Best explanation: Typical composition of an Inconel is chromium 20-23%, IRON 5%, molybdenum 8-10% and nickel around 60-65%. Inconel has the highest stress-corrosion RESISTANCE whereas ALUMINUM, stainless steel, and titanium are prone to stress corrosion CRACKING.

Correct option is (a) True

Explanation: High-silicon cast iron is the TYPE of alloy cast IRONS that are formed with high silicon content (up to 14%). The EXCELLENT corrosion RESISTANCE of these alloys is due to the formation of a passive SiO2 layer.

Right ANSWER is (a) True

Easiest explanation: COMPOSITES are the type of materials that are formed by the combination of two or more materials. And metallic composites CONSIST of a metallic matrix strengthened by metallic or nonmetallic fibers or whiskers. This includes boron, GRAPHITE, GLASS, and metal.

Correct ANSWER is (d) Iridium, palladium, and RUTHENIUM

The best I can explain: NOBLE metals are the metals that are characterized by highly positive potentials relative to the hydrogen electrode along with excellent corrosion RESISTANCE. This includes iridium, palladium, ruthenium, rhodium, osmium, gold, silver, and platinum.

Correct ANSWER is (b) HEXAMETHYLENE adipamide

To elaborate: The chemical name of NYLON (6.6) is hexamethylene adipamide. It is derived from the monomers of nylon that are HEXAMETHYLENEDIAMINE and adipic ACID.

The correct CHOICE is (d) Physical, mechanical and chemical properties

The explanation: Properties of a metal that is often required to consider by CORROSION engineers are:

Physical properties such as density, MODULUS of elasticity

Mechanical properties such as STRENGTH, hardness

Chemical properties such as corrosion resistance, reactivity.

The correct answer is (b) 3 parts of HYDROCHLORIC ACID and 1 PART of nitric acid

The explanation: The COMPOSITION of aqua regia is 3 parts of hydrochloric acid and 1 part of nitric acid. It corrodes/dissolves NOBLE metals such as gold, platinum, and palladium.

The CORRECT option is (a) Nickel

Easy explanation: Stainless STEEL is a generic term that attributes to the alloy SYSTEM of iron-carbon-chromium and nickel. Addition of nickel as alloying element up to 10% attributes in a rapid and large increase in stress-corrosion RESISTANCE of stainless steel.

The correct CHOICE is (d) Martensitic, ferritic and austenitic stainless STEELS

Best EXPLANATION: Stainless steel is a generic term that applies to iron-carbon-chromium and nickel alloy SYSTEM. Types of stainless steels are Martensitic stainless steels, ferritic stainless steels, austenitic stainless steels, and precipitation-hardened steels.

The correct choice is (d) It is an AMORPHOUS inorganic oxide, composed of pure silica and mostly TRANSPARENT in nature

For explanation: Glass is an amorphous inorganic solid, mostly silica, COOLED to a rigid condition without crystallization. Its transparency is USED for equipment such as flowmeters and glass FIBERS.

Correct option is (c) Modulus of elasticity

Easiest explanation: At a CERTAIN point, modulus of elasticity is considered as the physical PROPERTY of a metal. Because it is an inherent property that cannot be CHANGED by HEAT TREATMENT or cold working.

The correct choice is (d) Bakelite, Durez, and RESINOX

Explanation: Phenolics materials such as Bakelite, Durez, and Resinox are made up of PHENOL and formaldehyde. It uses for various applications such as ELECTRICAL sockets, telephones, VALVES, and coatings.

The correct option is (a) True

The BEST explanation: Corrosion of plastics is not the same as that of metals. Corrosion of metals results in the DISSOLUTION of metal ions whereas corrosion or degradation of plastics is due to swelling, LOSS of mechanical properties, softening, hardening, and spalling.

Right answer is (a) VITREOUS silica

For explanation I WOULD say: Vitreous silica is also CALLED FUSED silica. It has better thermal properties and corrosion resistance at high temperatures than most ceramics. Whereas amethyst, citrine, and rutilated QUARTZ are the types of quartz.

Right option is (d) Brittle in nature, less tensile STRENGTH and less RESISTANCE to thermal SHOCKS

Explanation: Disadvantages of CERAMIC materials are:

i. Brittle in nature

ii. Less tensile strength

iii. Less resistance to thermal shocks.

Right answer is (d) BRICK, stone and fused SILICA

The EXPLANATION: Examples of CERAMICS are brick, stone, fused silica, stoneware, glass, clay, porcelain, concrete, abrasives, MORTARS, and high-temperature refractories.

Correct CHOICE is (b) Titanium, stainless STEELS, and aluminum and its alloys

To EXPLAIN I would say: Corrosion resistance of the metal is the ability of a metal to withstand the effect of a corrosive environment. Titanium, stainless steel, and aluminum and its alloys will RESIST the corrosive environment with the formation of their oxide LAYER.

Right option is (c) HASTELLOY C and MONEL

Easiest explanation: Hastelloy C and Monel are corrosion-resistant metals to hydrofluoric ACID. Whereas titanium and most other metals USUALLY CORRODE in hydrofluoric acid.

Correct option is (a) True

To explain: Acid brick is the material MADE from FIRECLAY with a silica content about 10% greater than ORDINARY firebrick. It is usually USED for the CONSTRUCTION of the floor of steel tanks that are subjected to acid spillage.

Right option is (d) Polypropylene, polystyrene and polyvinyl chloride

To elaborate: Thermoplastics are the TYPE of plastics that soften on HEATING and return to their original hardness when cooled. Polypropylene, polystyrene, polyethylene, FLUOROCARBONS, and polyvinyl chloride are EXAMPLES of thermoplastics.

Correct ANSWER is (c) Polymethyl methacrylate

Best explanation: Polymethyl methacrylate is the POLYMER of many METHYL methacrylate MONOMERIC units. It is used for making eye LENSES as it is transparent to light. It is usually denoted as PMMA.

The correct CHOICE is (d) Thermoplastics and thermosetting

The best I can EXPLAIN: Plastics can be categorized based on various PARAMETERS such as MONOMER units, temperature behavior, and structure. Thermoplastics and Thermosetters are the TWO types of plastics based on thermal behavior.

The CORRECT answer is (c) Both Hexamethylenediamine and adipic ACID

The best I can explain: Hexamethylenediamine and adipic acid are the two monomers of NYLON (6,6). The chemical FORMULA of hexamethylenediamine and adipic acid is NH2-CH2-CH2-CH2-CH2-CH2-CH2-NH2 and HOOC-CH2-CH2-CH2-COOH respectively.

Right choice is (d) MAGNESIUM, sodium, and molybdenum

Easiest EXPLANATION: If the Pilling-bed worth ratio of a particular metal is less than 1 then it results in a porous, VOLATILE, and thin oxide layer. Sodium, molybdenum, and magnesium are examples of this kind.

Correct option is (B) BULK metallic glasses

The explanation: Bulk metallic glasses are the non-crystalline alloys that are formed with low critical cooling rates. These bulk metallic glasses EXHIBIT useful engineering properties such as HIGH mechanical strength and high corrosion RESISTANCE.

The correct ANSWER is (a) Oak, redwood, and pine

Explanation: GENERALLY, wood is not a corrosion-resistant material but in PARTICULAR circumstances, it can be used in the ACCOUNT of being economical. CYPRESS, pine, oak, and redwood are the types of woods used for corrosion applications.

Right choice is (a) It softens on heating and returns to original HARDNESS on cooling

To EXPLAIN: Thermoplastics is ONE of the TYPE of plastics which softens on heating and returns to original hardness on cooling. Fluorocarbons, POLYETHER, and nickel are examples of thermoplastics.

Right CHOICE is (a) CADMIUM

To elaborate: Corrosion fatigue is the simultaneous effect of fatigue and corrosion on a working metal. Cadmium plating is USED for high-strength steels in aircraft to improve resistance to corrosion fatigue.

Right option is (d) Sulfates, OXIDES, and phosphates of lead

For explanation: Lead and its ALLOYS are usually used piping, RADIATION shield, and storage batteries. It is resistant to corrosion in sulfuric ACID, CHROMIC acid, and phosphoric acid. Sulfates, oxides, and phosphates of lead are the corrosion products of lead that act as protective films.

The correct CHOICE is (d) High corrosive resistance, good strength-weight RATIO, and nontoxic corrosion PRODUCTS

To explain I would say: The properties of ALUMINUM that contribute to its widespread APPLICATIONS are high corrosion resistance, good strength-weight ratio, nontoxic corrosion products, appearance, and electrical and thermal conductivity.

Correct OPTION is (b) Fiber-REINFORCED plastic

The explanation: FRP can be abbreviated as Fiber-reinforced plastic regarding reinforced PLASTICS. Carbon fibers, alumina fibers, an ARAMID fiber can be reinforced into plastics for better STRENGTH and corrosion resistance.

The CORRECT answer is (a) Mylar

The BEST explanation: Thermosetting POLYMERS such as Mylar, Dacron, Vibrin, and Dypol are categorize under polyester. The satellite was made of thin, reflective Mylar FILM.

Correct OPTION is (c) Magnesium, zinc and magnesium

Explanation: Sacrificial metals are the metals that corrode preferentially over the metallic structure that needs to be protected. This cathodic PROTECTION works on the principle of the GALVANIC effect. TIN, zinc, magnesium are the common sacrificial metals USED.

The correct OPTION is (d) Resistance to SEAWATER, chloride salt solutions, hypochlorite’s, wet CHLORINE and fuming nitric acid

Easy explanation: Titanium is an EXCELLENT corrosion-resistant metal in many corrosive environments. The CHARACTERISTICS of titanium that account for much of its application in corrosion services are its resistance to seawater, chloride salt solutions, hypochlorite’s, wet chlorine, and fuming nitric acid.

The correct option is (a) True

To elaborate: Silicones are used for the molding compounds, LAMINATING resins, and INSULATING for electric motors and ELECTRONIC EQUIPMENT because of its outstanding heat resistance. It can be demonstrated by Si–O–Si bond with alkyl groups on EITHER side of the silicon atom.