Answer: b [Reason:] Wet analysis is a method of testing for mechanical composition. This technique is accurate but is time-consuming. Wet techniques for iron-base and copper alloys are straightforward. However, there are difficulties measuring boron in boron-treated steels, magnesium in ductile iron, and for carbon contents less than 0.04%.

Answer: a [Reason:] In a spectrometer, only selected wavelengths are recorded through entrance slits. These are dispersed by the grating and then go through exit slits for a particular set of elements. Airpath spectrometer does not allow determination and analysis of carbon and sulfur, whereas vacuum spectrometer does.

Answer: d [Reason:] For a spectrograph, the complete spectrum is recorded on a black-and-white 35 mm film. Densitometer then measures the blackness of lines, from which the concentration can be calculated. A quantometer is a separate device used for automatic quantitative analysis in spectroscopy.

Answer: b [Reason:] A metal to be analyzed by XRF or OES requires a specially poured, chill-cast sample to retain the elements in solution and maintain homogeneity. XRF is most accurate at concentrations of about 0.1-50% whereas OES is most accurate for concentrations of 0.0001-2%.

Answer: d [Reason:] Visual inspection is the simplest, fastest, and most commonly employed inspection technique. However, it requires greater skills of the inspector to identify the defects. It is mostly used for castings such as manhole covers, drains, counterbalance weights etc.

Answer: a [Reason:] Certain defects such as internal shrinkage, porosity, blowholes, and slag inclusions affect the casting soundness. These can be detected by a hammer test. Here, the casting is suspended above the floor, struck with a hammer at different places, and the sound produced is carefully noted.

Answer: c [Reason:] Radiography is done by exposing the components to short wavelength radiation in the form of x-rays or gamma-rays. These rays are derived from a source like an x-ray tube or cobalt-60.

Answer: b [Reason:] Most defects such as blow holes, porosity, cracks etc., possess less density than the sound of metal casting. As a result, they transmit x-rays better than the sound metal does. This gives the film a dark appearance where the defects are present. The exposed and developed x-ray film showing light and dark areas is termed as a radiograph or an exograph.

Answer: d [Reason:] Gamma-rays are used for detecting small defects in casting sections less than 50 mm as well as castings thicker than those in x-rays. Gamma-rays are better for examination of varying thickness due to less scatter. X-ray is a much quicker method requiring seconds or minutes, whereas gamma-ray method requires hours.

Answer: c [Reason:] To conduct a microscopic study, a sample must be removed from an area close to the failure. If the material is soft, manual hacksawing is done to cut the sample. If the material is hard, however, abrasive cutoff wheels are employed.

Answer: c [Reason:] Whenever possible, it is preferred that the size of the specimen must be such that it is easy to handle. For this purpose, the soft and hard specimen may be rough-ground on a belt sander. The rough grinding is continued until the surface is flat and free from irregularities.

Answer: b [Reason:] The most common thermosetting resin used for mounting is bakelite. It is available in a variety of colors and helps easily identify the specimen.

Answer: c [Reason:] Bakelite, along with the specimen, is placed in a mounting press for the mounting process. The temperature is gradually increased to 150oC and a molding pressure of 4000 psi is applied at the same time.

Answer: a [Reason:] Lucite is a completely transparent thermoplastic resin which is used for mounting. This transparency helps observe the exact section that is being polished. Here, these resins do not undergo any curing at the molding temperature.

Answer: d [Reason:] After the heating coil is removed, the cooling fins are inserted which cool the mount below 75oC in about 7 minutes. Ejecting the mold while it is hot or allowing it to cool slowly causes the mount to turn opaque.

Answer: b [Reason:] After mounting, the specimen is polished using emery paper, which is usually done dry. For soft materials, however, silicon carbide is used due to its higher rate of removal.

Answer: c [Reason:] The gamma form of aluminum oxide is widely preferred for fine polishing of ferrous and copper-based materials. Cerium oxide is also used for fine polishing of aluminum, magnesium, and their alloys. Other abrasives used are a diamond paste, chromium oxide, and magnesium oxide.

Answer: a [Reason:] Polishing cloths are chosen carefully based on the types of material and nature of the study. Among synthetic polishing cloths, Gamal and Microcloth are two of the most widely used varieties.

Answer: b [Reason:] After mounting, the specimen is polished using emery paper containing fine abrasives. It starts by using No.1 paper, and then progresses to 1/0, 2/0, 3/0, and finally 4/0. Black spots found on magnification are oxide impurities of the specimen or mount.

Answer: b [Reason:] Lead is the oldest of the commonly used metals and is the softest of the heavy metals. It is a poisonous element. Lead has an FCC crystal structure.

Answer: a [Reason:] Lead is a heavy metal with a low melting point of 327 and a boiling point of 1749. It has a density of 11.34 kg/dm³. Lead also possesses low strength, hardness, and elasticity.

Answer: b [Reason:] When lead is cast or cut, it initially appears in a lustrous silvery-blue color. However, after some time, it turns into a metallic-grey element. This is due to oxidation process when it is exposed to air.

Answer: b [Reason:] Bearing metals are anti-friction materials which may be derived from lead alloys containing 8-10% lead. Lead compounds include red lead and white lead.

Answer: d [Reason:] Bearing metals, composed of lead and tin alloys, are used for friction bearings. When antimony is added, they are known as Babbit metals. Addition of antimony makes the alloy hard.

Answer: c [Reason:] Nickel is a metal having a melting point of 1453^oC and a boiling point of 2730^oC. It is silvery-gold in appearance and is lustrous.

Answer: a [Reason:] Invar is a trademark for an iron-nickel alloy containing 40-50% nickel. It possesses an extremely low coefficient of thermal expansion. It is used for making precision instruments, measuring tapes etc.

Answer: c [Reason:] Invar is an alloy of nickel and iron. However, when 12% of chromium is used instead of iron, it produces Elinvar alloy. It possesses a low coefficient of expansion and an invariable modulus of elasticity.

Answer: c [Reason:] Monel is a nickel-based alloy with copper. H Monel is a hard-casting grade Monel. K Monel and S Monel are known as age-hardenable grade and age-hardenable casting grade respectively. R monel is a free machining grade.

Answer: b [Reason:] Monel usually contains 66% Ni, 31.5% Cu, 1.35% Fe, and 0.9% Mn. They are stronger and tougher when compared to mild steel, and have excellent resistance to atmospheric and seawater corrosion. It has a brighter appearance when compared to nickel.

Answer: b [Reason:] Coercive force is that opposing magnetizing force which removes any preceding magnetizing effect. Permeability is the attribute which helps the magnetic field to be constructed. Hysteresis is the lag in magnetization due to variations in the magnetic field.

Answer: a [Reason:] Magnetic permeability is defined as the ratio of magnetic induction to the intensity of magnetic field ( ), whereas relative permeability is the ratio of permeability of medium to the permeability of free space ( ). Magnetization is defined by the equation , and ferromagnetism is the ratio of the intensity of magnetization to the intensity of magnetic field ( ).

Answer: a [Reason:] The magnetic permeability of Iron (Fe) for 99.95% purity is 2.5 * 10^-1 whereas its relative permeability is 2 * 10⁵. Permeability and relative permeability values, decrease for lower purity levels of iron. The magnetic permeability of carbon steel is 1.26 * 10^-4 whereas its relative permeability is 100.

Answer: c [Reason:] Emissivity is defined as the effectiveness of emitting energy and thermal radiation. It is often also known as absorptivity. Luminance is the measure of luminous intensity. Refraction and reflection are the properties by which light changes direction, and change in a direction respectively.

Answer: a [Reason:] The emissivity of aluminum foil at room temperature is 0.03. The emissivity of polished silver and copper is 0.02 and 0.04 respectively, while that of concrete/brick is 0.9. Since emissivity is the ratio of the total emissive power of the body to the total emissive power of a perfectly black body, it does not have a unit.

Answer: c [Reason:] Alkalinity is the ability of a substance which neutralizes the acidic nature of the material. Corrosion resistance is its ability to resist corrosion. Chemical equilibrium is the state in which the reactant and product do not vary anymore with time.

Answer: d [Reason:] Castability is the ability of a metal or alloy by which a perfect cast is formed. The ease with which a material can be machined is known as machinability. The solderability is the ease with which a soldered joint can be prepared.

Answer: c [Reason:] Soft cast iron is a common construction material, which possesses a machinability index of 80. The machinability indexes of standard steel, ball bearing steel and cast copper are 100, 30, and 70 in that order.

Answer: b [Reason:] Tin solder 35, which contains 35% of Sn and 65% of Pb, is used for plumbing work. Tin solder 20 is used for tinning and filling of seams, while Cd-Sn is used for secondary soldering with the composition of 50% Sn and 17% Cd. For difficultly soldered materials, Zn-Cd is used in 17 to 83 ratios.

Answer: b [Reason:] Porosity is that property of a material which helps it to absorb lubricants, while density is the measure of the weight of unit volume. The solderability is the ease with which a soldered joint can be prepared. Absorptivity is an optical property of materials.

Answer: c [Reason:] A special type of sand is used for making molds, which is an important stage in casting. The molding sand contains refractory sand, binder, and additive. These type of sands maintain the shape at high temperatures, makes it porous, and is cheap, thereby reusable.

Answer: c [Reason:] Silica sand is widely used as a molding sand. It contains 80-90% silicon dioxide. The silica gives refractoriness to the sand. The silica sand is cheap, easily available, has high thermal stability, and can be reusable.

Answer: d [Reason:] Depending on the amount of clay content, molding sand can be classified into various types. Silica sand contains up to 2% clay, whereas weak sand contains 2-10% clay. Moderately strong sand has 10-20% clay, strong sand has up to 30% clay, and loam sand has up to 50% clay.

Answer: b [Reason:] Natural sand, as the name suggests, is available as a natural deposit. These contain about 80-90% silica, 5-10% clay, and a small amount of lime and magnesia. These sand require only 5-8% water.

Answer: d [Reason:] Chromite sand is a special kind of sand which has good refractoriness, high heat conductivity, and low expansion ratio. It is mainly used for making chilled castings. It may also be used as facing sand in steel casting.

Answer: b [Reason:] Clay binders are the most common types of inorganic binder as they are natural earthy material. The most common types of clay used in molding sand are fireclay, kaolinite, and bentonite. Kaolinite and bentonite clays are useful as they have high thermo-chemical stability.

Answer: a [Reason:] Additives are added to the molding sand to improve the properties of the mold. Seacoal is a finely powered bituminous coal used to obtain smoother and cleaner surfaces of castings. Sawdust used in dry conditions improves the permeability and deformability of the molds.

Answer: a [Reason:] The sand which is in moist state is known as green sand. It contains about 5-8% water and 16-30% clay. It is soft, light, and porous, and is used for simple and small-sized castings.

Answer: b [Reason:] Molding sand is prepared in three stages. The mixing stage involves mixing of sand, binding, moisture, and additives. Then the sand is tempered by spraying and mixing water in the muller. Finally, the sand is conditions to remove foreign materials, aerating the sand, and other processes.