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Multiple choice question for engineering

Set 1

1. Which of these materials is not added to iron for improving its oxidation resistance?
a) Nickel
b) Chromium
c) Aluminum
d) Silicon

View Answer

Answer: d [Reason:] Alloying elements in sufficient quantities are added to iron to improve their oxidation resistance. Nickel, chromium, and aluminum are the most common of these alloying elements.

2. How much chromium is required to provide oxidation resistance for use over 1000oC?
a) 1%
b) 6%
c) 12%
d) 17%

View Answer

Answer: d [Reason:] Chromium is added to materials to improve oxidation resistance. Up to 10% chromium is added to oil refinery parts and up to 12% is added for operations up to 1000oC. Over this temperature, 17% chromium is added.

3. Molybdenum with hydrogen can be used up to ________
a) 1000oC
b) 1500oC
c) 2000oC
d) 4000oC

View Answer

Answer: b [Reason:] Molybdenum in a protective coating of hydrogen can be used for oxidation resistance. It is mainly used in furnace windings up to 1500oC.

4. 10% chromium mixed with ______ can be used up to 1100oC.
a) Nickel
b) Chromium
c) Aluminum
d) Silicon

View Answer

Answer: a [Reason:] 10% chromium alloyed with nickel results in an element known as chromel. This element, along with alumel (2% Al, 2% Mn, 1% Si, and Nickel) can be used up to a temperature of 1100oC.

5. Which of these metals does not require alloying for oxidation resistance?
a) Iron
b) Copper
c) Aluminum
d) Molybdenum

View Answer

Answer: c [Reason:] Molybdenum is generally covered with a protective oxide coating while titanium acts as one. As a result, no alloying elements are used to improve their oxidation properties, unlike elements like copper and molybdenum.

6. _________ is used to prevent duralumin from corrosion.
a) Iron
b) Kynal
c) Titanium
d) Alclad

View Answer

Answer: d [Reason:] Alclad is a substance used to prevent corrosion of duralumin. It is made by covering each side of duralumin with a layer of pure aluminum sheets.

7. Galvanized ion is made by dipping low carbon steel in molten zinc at ________
a) 100oC
b) 150oC
c) 200oC
d) 450oC

View Answer

Answer: d [Reason:] Galvanized ion (G.I.) is prepared by dipping a low carbon steel sheet in a molten bath of zinc at around 450oC. When cooled, the zinc coating crystallizes and forms ‘zinc flowers’.

8. Which of these is not a way to prevent intergranular corrosion?
a) Reduction of carbon level
b) Quenching
c) Addition of carbide forming elements
d) Reduction of alloying elements

View Answer

Answer: d [Reason:] Improper heat treatment of 18/8 stainless steel may result in intergranular corrosion. It can be prevented by shrinking of carbon level to less than 0.05%, quenching from high temperature, and the addition of strong carbide forming elements to the steel.

9. Dezincification of brass is prevented by addition of ________
a) Nickel
b) Zinc
c) Arsenic
d) Tungsten

View Answer

Answer: c [Reason:] Dezincification is a special type of corrosion that occurs in alpha brass. It can be controlled by adding 0.04% of arsenic to brass.

10. Season-cracking can be prevented by cold-working of brass at _________
a) 15oC
b) 100oC
c) 300oC
d) 550oC

View Answer

Answer: c [Reason:] Cold-worked brass with high residual stresses along the grain boundary is known as season-cracking. This generally occurs in the presence of ammonia. This corrosion can be prevented by cold-working at 300oC.

11. How can caustic embrittlement be avoided?
a) Addition of nickel
b) Increasing potential
c) Decreasing carbon
d) Adding tannins

View Answer

Answer: d [Reason:] Caustic embrittlement is caused in boilers due to the stress and high concentration of hydroxyl ions. This can be prevented by addition of tannins and phosphates.

Set 2

1. Cryogenics deal with temperatures around _________
a) -50oC
b) -90oC
c) -180oC
d) -250oC

View Answer

Answer: c [Reason:] Cryogenics is defined as the study of materials at a low temperature. This often stands at -150oC in general use but has a standard set by National Institute of Standards and Technology as -180oC. This comes into consideration due to the boiling point of gases.

2. What is the boiling point of nitrogen?
a) 20.27
b) 27.09
c) 77.36
d) 111.7

View Answer

Answer: c [Reason:] Cryogenics refers to the study and production of materials under low temperatures. The boiling points of cryogenic fluids like hydrogen, neon, nitrogen, and methane are 20.27K, 27.09K, 77.36K, and 111.7K in that order.

3. Liquid oxygen is produced by ____________ method
a) Batch distillation
b) Steam distillation
c) Extractive distillation
d) Fractional distillation

View Answer

Answer: d [Reason:] Liquid oxygen (Lox) is a common cryogenic gas commonly used in aerospace and medical applications. It is formed from the oxygen in air by fractional distillation method.

4. What is the appearance of liquid nitrogen?
a) Yellow
b) Colorless
c) Bluish-gray
d) Black

View Answer

Answer: b [Reason:] Liquid nitrogen is a cryogenic liquid formed from nitrogen at low temperatures. It is a colorless liquid that results in brisk freezing.

5. How can cryogenic temperatures lower than 30,000K be measured?
a) Silicon diode
b) Calorimeter
c) Superconducting granules
d) Roton detector

View Answer

Answer: a [Reason:] Cryogenic particle detectors often operate around absolute zero temperature. Up to 30,000K, resistant thermometers like PT-100 sensor are used. Below this temperature, silicon diode is used for measurement of temperature.

6. Cold working is generally carried out __________
a) Below melting point
b) Above recrystallization temperature
c) At room temperature
d) Cryogenic temperature

View Answer

Answer: c [Reason:] Cold working is defined as the plastic deformation of a material which results in strain hardening. It usually occurs at room temperature. Hot working is generally carried out above recrystallization temperature but below its melting point.

7. How does hot working affect grain structure?
a) Refines it
b) Distorts it
c) Warps it
d) Has no effect

View Answer

Answer: a [Reason:] Although hot working refines the grain structure of the material, it does not improve its surface finish. Cold working, on the other hand, improves surface finish while distorting the grain structure.

8. Which of the following is an application of hot working?
a) Shapes the metal
b) Finishing
c) Thinning of material
d) Dimensional accuracy

View Answer

Answer: a [Reason:] Hot working of materials is done to help shape the metal and produce raw material for cold working. Cold working, on the other hand, is used for finishing, thinning, and improving mechanical properties while also improving dimensional accuracy of the metal.

9. Which of the following is a drawback of cold working?
a) Oxide formation
b) Surface scaling
c) Decarburization
d) Low ductility

View Answer

Answer: d [Reason:] When hot worked, surface scaling and decarburization of the material occurs, with the formation of oxide. On cold working, the cold worked part may experience strain hardening and less ductility.

10. Which of the following is a hot working process?
a) Stamping
b) Squeezing
c) Forging
d) Bending

View Answer

Answer: c [Reason:] Forging, pipe welding, and spinning are the most commonly employed hot working processes, whereas those of cold working include pressing and deep drawing, tamping, squeezing, bending, and shearing. Rolling and extrusion methods are common to both hot and cold working.

11. What is the hot rolling temperature of mild steel?
a) 200oC
b) 450oC
c) 1000oC
d) 1200oC

View Answer

Answer: c [Reason:] Hot rolling is carried out at a temperature above 0.7 Tm. Here, Tm is known as the melting point temperature in Kelvin. This temperature is at 1000oC for mild steel and 450oC for aluminum.

12. Which rolling mill does the following figure illustrate?
engineering-materials-metallurgy-questions-answers-hot-cold-working-metals-q7
a) Three-high
b) Four-high
c) Cluster
d) Tandem

View Answer

Answer: d [Reason:] This picture is that of a tandem mill containing two or three four-high rolling mills. A four-high rolling mill is a roll stand containing four parallel rolls one above the other.

13. Cold forging is done for _________
a) Improving strength and hardness
b) Adding forging scale
c) Eliminating carburization
d) Rough surface finish

View Answer

Answer: a [Reason:] Cold forging processes are carried out to improve strength, hardness, and surface finishing while eliminating a forging scale and decarburization. They are commonly employed for making rivets, bolts, and nails. Cold heading is one such cold forging process.

14. Which of the following is a characteristic of hot rolling?
a) Refines grain structure
b) Economic
c) Slow speed
d) Uniform size

View Answer

Answer: c [Reason:] Hot rolling is carried out at temperatures above 0.7 Tm. It is stopped about 100-200oC above the critical temperature to prevent strain hardening. This process has a high speed of rolling, is economic, refines the coarse grain, and produces uniformity in the size of products.

15. __________ involves hammering of heated bars inside closed impression dies.
a) Press forging
b) Drop forging
c) Hammer forging
d) Upset forging

View Answer

Answer: b [Reason:] Drop or die forging is a slow process which involves hammering of heated bars of metal inside closed impression dies. It is used to make small parts weighing a few grams to even heavy parts weighing several kilograms. It is used for complex shapes like connecting rods and crankshafts.

Set 3

1. Which of the following is a point defect in crystals?
a) Edge dislocation
b) Interstitialcies
c) Grain boundaries
d) Cracks

View Answer

Answer: b [Reason:] Crystal defects are classified as point defects, line defects, and boundary defects. Point defects include vacancies, impurities, interstitialcies, and electronic defects.

2. How can the number of defects be determined?
engineering-materials-metallurgy-questions-answers-crystal-defects-q2

View Answer

Answer: a [Reason:] The number of defects at equilibrium at a definite temperature can be determined using the equation Ne(-Ed⁄kT). It is denoted by nd. Here, N stands for the total number of atomic spots and Ed is the activation energy.

3. The defect that occurs due to a displacement of an ion is known as __________
a) Vacancy defect
b) Schottky defect
c) Frankel defect
d) Interstitial defect

View Answer

Answer: c [Reason:] Frankel defect occurs due to a displacement of an ion from the crystal lattice. It is related to the interstitial defect, where an ion simply occupies a position between regular atoms.

4. Which defect does the following figure depict?
engineering-materials-metallurgy-questions-answers-crystal-defects-q4
a) Vacancy defect
b) Schottky defect
c) Frankel defect
d) Interstitial defect

View Answer

Answer: b [Reason:] When a pair of positive and negative ions both disappear from a crystal lattice, the effect is called a Schottky defect. It is closely related to vacancy defects where simply an ion is missing.

5. Which of these is a Frankel defect?
a) engineering-materials-metallurgy-questions-answers-crystal-defects-q5a
b) engineering-materials-metallurgy-questions-answers-crystal-defects-q5b
c) engineering-materials-metallurgy-questions-answers-crystal-defects-q5c
d) engineering-materials-metallurgy-questions-answers-crystal-defects-q5d

View Answer

Answer: a [Reason:] Frankel defect occurs due to a displacement of an ion from the crystal lattice while retaining all of the ions, unlike other defects. It is related to the interstitial defect, where an ion simply occupies a position between regular atoms.

6. Which defect does the following diagram represent?
engineering-materials-metallurgy-questions-answers-crystal-defects-q6
a) Vacancy defect
b) Schottky defect
c) Frankel defect
d) Interstitial defect

View Answer

Answer: d [Reason:] Interstitial defects occur when an atom occupies an empty position in a crystal lattice. Self-interstitial effects occur due to their own atoms, while others occur due to a foreign substance.

7. _______ occurs when a foreign substance replaces an atom in a crystal.
a) Vacancy defect
b) Substitutional impurity
c) Frankel defect
d) Interstitial impurity

View Answer

Answer: b [Reason:] A substitutional impurity occurs due to the occupation of a foreign atom in place of an atom in a crystal. On the other hand, interstitial impurities occur when a regular atom occupies a random space in the crystal lattice.

8. A disturbance in a region between two ideal parts of a crystal is known as ________
a) Boundary defect
b) Point defect
c) Line defect
d) Volume defect

View Answer

Answer: c [Reason:] Line defect is regarded as a disturbed region between two perfect parts of a crystal. They may be of either edge dislocation type or screw dislocation.

9. In screw dislocation, the Burger’s vector lies _________ to the dislocation line
a) Perpendicular
b) Parallel
c) At an angle
d) Sideways

View Answer

Answer: b [Reason:] The Burger’s vector in screw dislocation lies parallel to the dislocation line along the axis of a line of atoms in the same plane. On the other hand, it lies at an angle for edge dislocation.

10. Generation of dislocations can be identified using _______
a) Schottky mechanism
b) Burger’s vector
c) Twist
d) Frank-Read mechanism

View Answer

Answer: d [Reason:] The Frank-Read mechanism uses the Frank-Read source and its operation as a dislocation multiplier. The Frank-Read source contains a fixed lined at the X and Y nodes. Under the application of stress, the dislocation line expands and is further operated until it becomes readable.

11. What are one-dimensional defects?
a) Boundary defect
b) Point defect
c) Line defect
d) Volume defect

View Answer

Answer: c [Reason:] When compared geometrically, line defects are seen as one-dimensional defects. Line defects are also known as dislocations, with common types as edge and screw dislocations.

11. What are two-dimensional defects?
a) Boundary defect
b) Point defect
c) Line defect
d) Volume defect

View Answer

Answer: a [Reason:] The defects that occur on the surface of a material are known as surface or boundary defects. Geometrically, they are regarded as two-dimensional defects.

13. How is the dislocation energy defined?
a) J m-1
b) J m-2
c) m-2
d) N m-1

View Answer

Answer: a [Reason:] Dislocation energy is defined ad joule per meter and is denoted by E. Dislocation density is defined as meter per cubic meter or simply as per meter square.

Set 4

1. Which defect does the following image denote?
engineering-materials-metallurgy-questions-answers-defects-machining-metals-q1
a) Orange peel
b) Sinking
c) Burr and bend
d) Wrinkling

View Answer

Answer: a [Reason:] Whenever a coarse grain material blank is drawn, they will often be seen as a rough surface. The metal surface experiences roughness like that or an orange peel. This is known as the orange peel effect.

2. Which defect is illustrated in the below figure?
engineering-materials-metallurgy-questions-answers-defects-machining-metals-q2
a) Earing
b) Sinking
c) Burr and bend
d) Strain hardening

View Answer

Answer: a [Reason:] Cold working causes uneven deformation of the material, leading to the formation of ears. To minimize earing, excessive deformation in deep drawing must be avoided.

3. Which of the following is a chipless machining method?
a) Broaching
b) Reaming
c) Abrasive machining
d) Electrical discharge

View Answer

Answer: d [Reason:] Chip machining forms chips due to the action of the tool being inserted into the work piece. The common chip-type machining processes are drilling, boring, planning, reaming, etc. In chipless machining, the material is removed by chemical, electrochemical, or erosion method.

4. Wrinkling is caused due to _______
a) Compressive stress
b) Tensile stress
c) Improper clearance
d) Excessive deformation

View Answer

Answer: a [Reason:] Wrinkling is a sheet metal defect caused due to buckling under compressive stresses. It may also occur between a punch and a blank holder.

5. Which of the following is not a stage of volume shrinkage?
a) Liquid contraction
b) Solid contraction
c) Gaseous contraction
d) Solidification contraction

View Answer

Answer: c [Reason:] Liquid contraction occurs when the metal is in a liquid state, whereas solid contraction occurs when the metal is solid and takes place after solidification. Solidification contraction occurs during the transition from liquid to solid state.

6. Seed crystals are formed due to _________ of melt.
a) Heating
b) Cooling
c) Overheating
d) Undercooling

View Answer

Answer: d [Reason:] A metal in molten state exhibits high energy. When this melt cools, it loses energy and forms crystals. When there are no nuclei to start crystallization, melt undercools and forms nuclei or seed crystals.

7. Crystal growth occurs in __________ manner.
a) Dendritic
b) Pyramidal
c) Granular
d) Linear

View Answer

Answer: a [Reason:] The crystal growth during solidification occurs in a dendritic style. Dendritic growth is caused by the development of small arms on branches of dendrites.

8. Which of the following holds true for pure metals?
a) Low ductility
b) High tensile strength
c) High yield point
d) Corrosion resistance

View Answer

Answer: d [Reason:] Pure metals like copper and aluminum generally possess excellent thermal and electrical conductivity. They also have higher ductility and corrosion resistance. However, they possess low tensile strength and yield point.

9. Pure metals generally solidify at _________ temperature.
a) Boiling
b) Freezing
c) Room
d) Cryogenic

View Answer

Answer: b [Reason:] Pure metals melt and solidify at the melting point or freezing temperature. The metal is in a liquid state above freezing point but is in the solid state below it.

Set 5

1. In which case can the rotating crystal method for determining crystal structure be used?
a) Single crystal
b) Polycrystalline
c) Fine-grained polycrystalline
d) Cold worked crystals

View Answer

Answer: b [Reason:] X-ray diffraction is a technique used for determining and examining the condition of a crystal structure. Laue method is used for single crystals or polycrystalline masses, rotating crystal method is applicable for single crystals, whereas the powder method is applicable for finely divided crystalline powder.

2. What is the resultant image formed for very fine grains in Laue back reflection method?
a) Few clear spots
b) Large number of spots
c) Continuous rings
d) Irregular spots

View Answer

Answer: c [Reason:] X-ray diffraction is a technique used for probing the state of a crystal structure. Laue back reflection method is used for single crystals or polycrystalline masses. In this method, for very fine grains of 0.0004 mm show a back reflection photograph of continuous rings which are doubly resolved.

3. When are irregular spots in Laue method formed?
a) Coarse grains > 0.04 mm
b) Fine grains 0.004 mm
c) Very fine grains 0.0004 mm
d) Cold worked

View Answer

Answer: d [Reason:] Laue back reflection method is used for examining and measuring the condition of single crystals or polycrystalline masses. For cold worked metal, the back reflection photograph has an irregular shape and outline of the spots. Cold working, thus, causes the spots to widen radially.

4. Which state of metal does this figure depict?
engineering-materials-metallurgy-questions-answers-diffraction-q4
a) Coarse grains > 0.04 mm
b) Fine grains 0.004 mm
c) Very fine grains 0.0004 mm
d) Distorted crystal

View Answer

Answer: d [Reason:] X-ray diffraction is a technique used for investigation of the state of a crystal structure. Laue back reflection method is used for single crystals or polycrystalline masses. The given figure depicts the distorted form of a crystal.

5. The intensity of the initial neutron in neutron diffraction is reduced by a factor of ________
a) 102
b) 103
c) 105
d) 107

View Answer

Answer: b [Reason:] For neutron diffraction, a nuclear reactor is used as the initial source of neutrons. However, the intensity of the initial neutron is reduced by a factor of about 103 in this operation. After further diffraction, the resulting beam is rather weak.

6. What is the relative neutron scattering power of iron?
a) 1.8
b) 5.4
c) 7.7
d) 11.4

View Answer

Answer: d [Reason:] Iron and cobalt generally have atoms of similar atomic numbers, which makes them difficult to study. Through neutron diffraction, the values can be clearly determined. Iron has a scattering power of 11.4, whereas it is only 1.0 for cobalt.

7. What is the relative X-ray scattering power of iron and cobalt?
a) 1 and 1
b) 4 and 6
c) 12 and 13
d) 26 and 27

View Answer

Answer: d [Reason:] Iron and cobalt generally have atoms of similar atomic numbers, which makes it difficult to study their structures. The relative X-ray scattering power of iron and cobalt is 26 and 27 respectively. However, these values can be clearly determined by neutron diffraction method.

8. Which bond has a fluctuating charge?
a) Dispersion
b) Dipole
c) Ionic
d) Covalent

View Answer

Answer: a [Reason:] A fluctuating net charge is formed in a dispersion bond since adjacent atoms in the molecule repel each other. The fluctuating charge on one molecule interacts with another, which results in a net attraction. Due to this, a dispersion bond is formed .

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