GE105 Engineering Materials Properties PDF

GE105-Engineering Materials Properties Important Questions with Answers Multiple Choice Questions: 1) Which of the following factors is not typically considered when selecting a material for engineering...

GE105-Engineering Materials Properties Important Questions with Answers Multiple Choice Questions: 1) Which of the following factors is not typically considered when selecting a material for engineering design? a) Density; b) Flexibility c) Color d) Corrosion resistance Answer: c) Color 2) What happens to water at 100°C under standard atmospheric pressure? a) It becomes ice b) It remains a liquid c) It changes from a liquid to a gas d) It turns into plasma Answer: c) It changes from a liquid to a gas 3) Which of the following questions would an engineer ask when selecting a material for a high-temperature application? a) How much does the material expand with increasing temperature? b) How easy is it to paint the material? c) Is the material magnetic? d) Can the material be molded into complex shapes? Answer: a) How much does the material expand with increasing temperature? 4) Which state of matter has free electrons and nuclei, often referred to as plasma? a) Solid b) Liquid c) Gas d) Plasma Answer: d) Plasma 5) What is the basic building block of all matter? a) Molecule b) Atom c) Electron d) Proton Answer: b) Atom 6) When designing materials for bioengineering applications, which of the following is an additional factor engineers must consider? a) Cost b) Machinability c) Toxicity to the body d) Flexibility Answer: c) Toxicity to the body 1 7. Which of the following is an example of a physical property? a) Corrosion resistance b) Malleability c) Thermal conductivity d) Ductility Answer: c) Thermal conductivity 8. Which of the following is a chemical property? a) Ductility b) Heat capacity c) Acidity d) Specific heat Answer: c) Acidity 9. The ability of a material to resist deformation under load is known as its ______. a) Toughness b) Strength c) Brittleness d) Conductivity Answer: b) Strength 10. Which property explains how a material behaves under heat? a) Optical properties b) Chemical properties c) Thermal properties d) Mechanical properties Answer: c) Thermal properties 11. Which of the following is an optical property? a) Absorption b) Tensile strength c) Thermal expansion coefficient d) Viscosity Answer: a) Absorption 12. The electrical property that describes a material's ability to conduct electricity is called ______. a) Resistivity b) Ductility c) Luminescence d) Specific heat Answer: a) Resistivity 13. In mechanical applications, which property is important for resisting deformation under shear forces? a) Modulus of elasticity b) Modulus of rigidity c) Corrosion resistance 2 d) Electrical conductivity Answer: b) Modulus of rigidity 14. Which of the following factors can influence the properties of a material? a) Processing method b) Age of the material c) Chemical composition d) All of the above Answer: d) All of the above 15. What is the unit of density in the SI system? a) kg/m² b) kg/m³ c) N/m² d) J/K Answer: b) kg/m³ 16. Which material has a density approximately one-third that of steel? a) Copper b) Aluminum c) Iron d) Brass Answer: b) Aluminum 17. Heat capacity is an extensive property because it depends on ______. a) The material's volume b) The material's temperature c) The material's density d) The size or quantity of the material Answer: d) The size or quantity of the material 18. The unit of thermal conductivity in the SI system is ______. a) W/m·K b) J/kg·K c) N/m² d) J/K Answer: a) W/m·K 19. At what point does a solid material transition to a liquid state? a) Boiling point b) Sublimation point c) Melting point d) Condensation point Answer: c) Melting point 20. Which material property is best suited for cooking utensils due to its ability to heat up and cool down quickly? a) High density b) Low specific heat capacity 3 c) High melting point d) Low thermal conductivity Answer: b) Low specific heat capacity 21. The melting point of a material is generally measured at what standard pressure? a) 50 kPa b) 100 kPa c) 200 kPa d) 150 kPa Answer: b) 100 kPa 22.The color of a substance is determined by ______. a) The density of the material b) The wavelength of light it reflects c) Its boiling point d) Its specific heat capacity Answer: b) The wavelength of light it reflects 23.What does chemical composition specify about a compound? a) Size and weight of the atoms b) Identity, arrangement, and ratio of chemical elements c) The color and texture of the compound d) The physical state of the compound Answer: b) Identity, arrangement, and ratio of chemical elements 24.What is the ratio of hydrogen to oxygen atoms in water (H₂O)? a) 2:2 b) 1:2 c) 2:1 d) 1:1 Answer: c) 2:1 25.What type of bond involves the sharing of electron pairs between two atoms? a) Ionic bond b) Covalent bond c) Metallic bond d) Hydrogen bond Answer: b) Covalent bond 26.What type of bond results from the electrostatic attraction between oppositely charged ions? a) Covalent bond b) Ionic bond c) Metallic bond d) Hydrogen bond Answer: b) Ionic bond 27.Which type of bond involves the delocalization of electrons among multiple metal atoms? 4 a) Covalent bond b) Ionic bond c) Metallic bond d) Hydrogen bond Answer: c) Metallic bond 28.Hydrogen bonding occurs between hydrogen and which type of atoms? a) Positively charged ions b) Highly electronegative atoms like N, O, or F c) Negatively charged ions d) Neutral atoms Answer: b) Highly electronegative atoms like N, O, or F 29.What is corrosion resistance? a) The ability of a material to withstand physical damage b) The ability to prevent chemical or electrochemical attack c) The ability to conduct heat d) The ability to expand under pressure Answer: b) The ability to prevent chemical or electrochemical attack 30.A substance with a pH of less than 7 is considered to be ______. a) Neutral b) Basic c) Acidic d) Alkaline Answer: c) Acidic 31.What is the ultimate strength of a material? A) The maximum deformation a material can undergo before failure B) The maximum stress a material can withstand before destruction C) The point at which a material starts to deform elastically D) The ability of a material to resist corrosion Answer: B 32.Ductility is measured by which of the following parameters? A) Percentage elongation (%EL) and percent reduction (%RA) B) Yield strength and ultimate strength C) Hardness and stiffness D) Toughness and resilience Answer: A 33.Which of the following is a characteristic of malleability? A) The ability to return to its original shape after deformation B) The ability to be flattened into thin sheets without breaking C) The resistance to wear and scratching D) The ability to be drawn into a wire Answer: B 5 34.Which of the following materials is considered brittle? A) Copper B) Glass C) Aluminum D) Mild steel Answer: B 35. What is the modulus of rigidity also known as? A) Tensile modulus B) Shear modulus C) Compressive modulus D) Elastic modulus Answer: B 36.Which material property indicates how easily a material can be formed into different shapes and sizes? A) Stiffness B) Formability C) Hardness D) Toughness Answer: B 37.What does a high modulus of elasticity indicate about a material? A) The material has high ductility B) The material is easy to twist C) The material requires a larger force to stretch or compress D) The material is prone to failure under tensile loads Answer: C 38.Which material property describes its ability to absorb energy before fracture? A) Modulus of resilience B) Modulus of toughness C) Stiffness D) Hardness Answer: B 39.What is thermal conductance (G)? a) A measure of a material's resistance to heat flow b) A measure of a material's ability to conduct heat c) A measure of a material's ability to store heat d) A measure of electrical resistance Answer: b) A measure of a material's ability to conduct heat 40. What unit is thermal resistance (R) measured in? a) Joules per kilogram (J/kg) b) Watts per Kelvin (W/K) c) Kelvin per Watt (K/W) d) Ohm-meters (Ω⋅m) 6 Answer: c) Kelvin per Watt (K/W) 41. Which material property describes the change in size with temperature change? a) Thermal resistance b) Coefficient of thermal expansion c) Specific heat capacity d) Electrical resistivity Answer: b) Coefficient of thermal expansion 42. What is the SI unit of specific heat capacity? a) Watts per meter b) Kelvin per Watt c) Joule per Kelvin per kilogram (J/kg.K) d) Ohm-meters (Ω⋅m) Answer: c) Joule per Kelvin per kilogram (J/kg.K) 43. What is electrical resistivity (ρ) a measure of? a) A material's ability to resist heat flow b) A material's ability to resist the flow of electricity c) A material's ability to conduct heat d) A material's ability to store energy Answer: b) A material's ability to resist the flow of electricity 44. Which of the following materials is considered a good conductor of electricity? a) Plastic b) Ceramics c) Copper d) Wood Answer: c) Copper 45. The temperature coefficient of resistance for conductors typically: a) Increases with increasing temperature b) Decreases with increasing temperature c) Remains constant with increasing temperature d) Becomes negative at high temperatures Answer: a) Increases with increasing temperature 46. What causes the refraction of light when it passes from one medium to another? a) Change in the wavelength of light b) Change in the speed of light c) Change in the direction of light d) Change in the frequency of light Answer: b) Change in the speed of light 47. Which of the following is an example of refraction? a) A mirror reflecting sunlight b) The twinkling of stars c) Light being absorbed by a black surface d) The heat radiated from a warm object 7 Answer: b) The twinkling of stars 48. What happens to light when it is reflected? a) It bends while passing through a medium. b) It is absorbed by the medium. c) It bounces back from the surface. d) It transmits through the medium. Answer: c) It bounces back from the surface. 49. In photosynthesis, the light absorbed by plants is converted into: a) Chemical energy b) Sound energy c) Kinetic energy d) Electrical energy Answer: a) Chemical energy 50. Which material property allows light to pass through it without significant scattering? a) Opaque b) Reflective c) Transparent d) Absorbent Answer: c) Transparent 51. What is the unit of luminous intensity? a) Candela b) Watt c) Lumen d) Joule Answer: a) Candela 52. Which of the following objects is a luminous object? a) The Moon b) A mirror c) The Sun d) A windowpane Answer: c) The Sun 53. What is the process by which sunglasses allow light to pass through but reduce its intensity? a) Reflection b) Refraction c) Absorption d) Transmission Answer: d) Transmission 54. Which of the following is NOT a lightweight metal? a) Aluminum (Al) b) Titanium (Ti) c) Copper (Cu) 8 d) Magnesium (Mg) Answer: c) Copper (Cu) 55. What is the primary reason aluminum is alloyed with other metals? a) To increase its electrical conductivity b) To reduce its density c) To improve its strength and corrosion resistance d) To make it more malleable Answer: c) To improve its strength and corrosion resistance 56. Which of the following is a common application of aluminum and its alloys? a) Nuclear reactors b) Cooking utensils and window frames c) Compressor blades of jet engines d) Electrical insulators Answer: b) Cooking utensils and window frames 57. Why are titanium alloys used in the aerospace industry? a) Due to their low density and corrosion resistance b) Due to their excellent thermal conductivity c) Due to their high strength-to-weight ratio and high-temperature resistance d) Due to their high electrical conductivity Answer: c) Due to their high strength-to-weight ratio and high-temperature resistance 58. Which lightweight metal has the lowest density among the following? a) Aluminum b) Titanium c) Magnesium d) Steel Answer: c) Magnesium 59. What property makes magnesium alloys suitable for use as sacrificial anodes? a) High strength-to-weight ratio b) Low electrical resistance c) Ability to corrode faster than other metals d) High thermal conductivity Answer: c) Ability to corrode faster than other metals 60. Which of the following is a key application of titanium alloys in commercial and military airplanes? a) Window frames b) Landing gear components and fuselage c) Beverage cans d) Electrical cables Answer: b) Landing gear components and fuselage 61. Magnesium alloys are commonly used in which of the following applications? a) Gas turbine engines b) Nuclear applications and dry cell batteries 9 c) Household mirrors d) Telescopes Answer: b) Nuclear applications and dry cell batteries 62. What is the primary reason for alloying pure metals? a) To reduce cost b) To enhance mechanical properties c) To make metals lighter d) To simplify the manufacturing process Answer: b) To enhance mechanical properties 63. Which of the following is a lightweight metal? a) Copper b) Iron c) Titanium d) Tungsten Answer: c) Titanium 64. Aluminum is commonly alloyed with which of the following metals to increase strength and corrosion resistance? a) Iron, nickel, and cobalt b) Copper, zinc, and magnesium c) Titanium, manganese, and silicon d) Tungsten, lead, and silver Answer: b) Copper, zinc, and magnesium 65. Brass is an alloy of which two elements? a) Copper and tin b) Copper and zinc c) Copper and nickel d) Copper and aluminum Answer: b) Copper and zinc 66. What is the main application of copper due to its high electrical conductivity? a) Aerospace components b) Home wiring c) Structural beams d) Car frames Answer: b) Home wiring 67. Which of the following types of steel contains more than 8% alloying elements? a) Carbon steel b) Low-alloy steel c) High-alloy steel d) Stainless steel Answer: c) High-alloy steel 68. What is the main advantage of using titanium in aerospace applications? a) Low cost 10 b) Excellent thermal conductivity c) High strength-to-weight ratio d) Corrosion resistance Answer: c) High strength-to-weight ratio 69. Cast iron typically contains what percentage of carbon? a) 0.015 - 2% b) 2 - 6.67% c) 10 - 30% d) 35% Answer: b) 2 - 6.67% 70. What are the three main ingredients of concrete? A) Aggregate, water, and air B) Aggregate, cement, and water C) Aggregate, sand, and gravel D) Cement, lime, and water Answer: B) Aggregate, cement, and water 71. Which of the following materials is commonly added to concrete in cold climates to accelerate curing? A) Sodium chloride B) Calcium carbonate C) Calcium chloride D) Potassium sulfate Answer: C) Calcium chloride 72. What is the primary reason for reinforcing concrete with steel bars? A) To improve aesthetic appearance B) To increase load-bearing capacity under tensile stress C) To reduce the weight of concrete D) To enhance thermal conductivity Answer: B) To increase load-bearing capacity under tensile stress 73. In which direction is wood generally stronger? A) Parallel to the grain B) Perpendicular to the grain C) Both directions equally D) Neither direction Answer: A) Parallel to the grain 74. What does a higher density of wood typically indicate? A) Lower strength B) Higher strength C) Increased moisture content D) Increased flexibility Answer: B) Higher strength 11 75. What type of timber is derived from coniferous trees? A) Hardwood B) Softwood C) Engineered wood D) Composite wood Answer: B) Softwood 76. Which type of concrete construction involves pre-fabricating components in a controlled environment? A) Cast-in-place concrete B) Precast concrete C) Reinforced concrete D) Prestressed concrete Answer: B) Precast concrete 77.What happens to the tensile stress in prestressed concrete once the tension in the steel rods is released? A) It increases significantly B) It becomes zero C) It becomes negative D) It remains unchanged Answer: B) It becomes zero 78. What are the two main categories of plastics? A) Bioplastics and synthetic plastics B) Thermoplastics and thermosets C) Rigid and flexible plastics D) Recyclable and non-recyclable plastics Answer: B) Thermoplastics and thermosets 79. Which of the following is an example of a thermoplastic? A) Phenol-formaldehyde resins B) Urea-formaldehyde resins C) Polyvinyl chloride (PVC) D) Epoxy resins Answer: C) Polyvinyl chloride (PVC) 80. Silicon is primarily found in nature as: A) Pure silicon B) Silicon dioxide (SiO2) C) Silicates D) Both B and C Answer: D) Both B and C 81.What characteristic makes silicon an excellent semiconductor? A) Its high thermal conductivity B) Its atomic structure 12 C) Its density D) Its elasticity Answer: B) Its atomic structure 82. Soda-lime-silica glass primarily consists of which materials? A) Sand, limestone, and soda ash B) Sand, quartz, and boron C) Silica, alumina, and calcium carbonate D) Silica, sodium chloride, and calcium oxide Answer: A) Sand, limestone, and soda ash 83. Which oxide is added to glass to create a yellowish stain? A) Copper oxide B) Silver oxide C) Aluminum oxide D) Magnesium oxide Answer: B) Silver oxide 84. What is the primary application of silica glass? A) Beverage containers B) Fiber optics C) Cookware D) Windows Answer: B) Fiber optics 85. Which type of plastic cannot be remolded once cured? A) Thermoplastics B) Biodegradable plastics C) Thermosets D) Composite plastics Answer: C) Thermosets 86. What are ceramic materials primarily composed of? A) Organic compounds B) Inorganic compounds C) Metallic compounds D) Composite materials Answer: B) Inorganic compounds 87. Which of the following is a characteristic of ceramics? A) High ductility B) Low thermal resistance C) Exceptional electrical properties D) High magnetic permeability Answer: C) Exceptional electrical properties 88. What is the primary application of silica glass fibers? A) Construction materials B) Data transmission in fiber optics 13 C) Food packaging D) Aerospace components Answer: B) Data transmission in fiber optics 89. Which type of fibers are typically used in fiber optics? A) Copper fibers B) Silica glass fibers C) Steel fibers D) Aluminum fibers Answer: B) Silica glass fibers 90. Composite materials are primarily made of: A) Single-phase materials B) Mixtures of different materials C) Metals only D) Polymers only Answer: B) Mixtures of different materials 91. What type of composite uses a polymer matrix? A) Metal-matrix composites B) Ceramic-matrix composites C) Polymer-matrix composites D) Reinforced concrete Answer: C) Polymer-matrix composites 92. In composite materials, what is the role of the matrix phase? A) Provide electrical insulation B) Enhance thermal conductivity C) Serve as a ductile support for the fibers D) Increase weight Answer: C) Serve as a ductile support for the fibers 93. Which composite material is commonly used in aerospace applications due to its lightweight and strength? A) Wood composites B) Metal alloys C) Polymer composites D) Reinforced concrete Answer: C) Polymer composites 94. What defines semiconductors? A) Materials that allow free flow of electrons B) Materials that block all electron flow C) Materials that allow some electron flow, positioned between conductors and insulators D) Materials that conduct electricity perfectly Answer: C) Materials that allow some electron flow, positioned between conductors and insulators 14 95. Which of the following is a common property of semiconductors? A) High conductivity B) High resistivity C) Low temperature coefficient of resistance D) Soft and malleable Answer: B) High resistivity 96. Which material is NOT a semiconductor? A) Silicon (Si) B) Germanium (Ge) C) Copper (Cu) D) Selenium (Se) Answer: C) Copper (Cu) 97. Semiconductors are used in which of the following applications? A) Structural materials B) Insulation C) Electronic devices, such as rectifiers and photocells D) Fuel production Answer: C) Electronic devices, such as rectifiers and photocells 98. Which of the following is a primary nuclear fuel? A) Iron (Fe) B) Uranium (U) C) Carbon (C) D) Lead (Pb) Answer: B) Uranium (U) 99. What is the role of moderators in nuclear reactors? A) To absorb neutrons B) To slow down neutrons C) To generate power D) To cool the reactor Answer: B) To slow down neutrons 100. Which material is often used as a control element in nuclear reactors? A) Silicon B) Beryllium C) Boron D) Thorium Answer: C) Boron 101. What is a characteristic of nuclear materials? A) They are primarily used for thermal insulation B) They produce high amounts of electricity without reaction C) They include metals and their alloys used in nuclear energy applications D) They are mainly organic compounds Answer: C) They include metals and their alloys used in nuclear energy applications 15 102. Fig.1 represent the stress-strain behavior of different materials. Identify which materials possesses more stiffness. (A) Material - A (B) Material - B (C) Material - C (D) Material A and C (E) None of the above (Ans: A) 103. Fig.1 represent the stress-strain behavior of different materials. Identify which materials possesses more in strength. (A) Material - A (B) Material - B (C) Material - C (D) Material A and C (E) None of the above (Ans: A) 104. Fig.1 represent the stress-strain behavior of different materials. Identify which materials possesses more ductility and or poor in stiffness. (A) Material - A (B) Material - B (C) Material - C (D) Material A and C (E) None of the above (Ans: C) Fill in the Blanks: 1) The smallest portion of a substance that retains its chemical properties is called a ______. Answer: molecule 2) The periodic table of elements shows 118 known ______ to date. Answer: chemical elements 3) Under standard atmospheric pressure, water becomes a gas at a temperature of ______ degrees Celsius. Answer: 100 4) The density of liquid water ______ with increasing temperature. Answer: decreases 5) A material’s resistance to corrosion is an important factor for selecting materials used in ______ environments. Answer: aggressive 6) The property that describes how a material reacts under electro-magnetic radiation is known as its ______ properties. 16  Answer: optical 7) The ability of a material to carry heat is described by its ______. Answer: thermal conductivity 8) The resistance of a material to the flow of electric current is called ______. Answer: resistivity 9) A material's ability to resist wear, impact, or deformation under load is referred to as its ______ properties. Answer: mechanical 10) The property of a material that determines its ability to expand when heated is called its ______. Answer: thermal expansion coefficient 11) Material properties such as strength, toughness, and elasticity fall under the category of ______ properties. Answer: mechanical 12) Density is defined as mass per unit ______. Answer: volume 13) The amount of heat energy required to raise the temperature of a given quantity of matter by one degree Celsius is called ______. Answer: heat capacity 14) The thermal conductivity of a material is often denoted by the symbol ______. Answer: k 15) The melting point is the temperature at which a solid begins to convert to a ______. Answer: liquid 16) The unit of heat capacity is ______ per degree Celsius. Answer: joules 17) The color of a substance is a result of the arrangement of ______ in its atoms. Answer: electrons 18) Chemical composition describes the number of ______ per molecule in a substance. Answer: elements 19) An ionic bond is formed when one atom ______ electrons to another atom. Answer: transfers 20) A covalent bond is formed when two atoms ______ electrons. Answer: share 21) Metallic bonds involve a large number of atoms sharing ______. Answer: delocalized electrons 22) Hydrogen bonds are a special type of ______ attraction between molecules. Answer: dipole-dipole 23) Corrosion degrades materials' mechanical strength, appearance, and ______ to liquids and gases. Answer: permeability 17 24) The internal resistance offered by a material to an externally applied force is called _______. Answer: stress 25) The property of a material that allows it to be drawn into wire is called _______. Answer: ductility 26) The ability of a material to return to its original shape after the removal of a load is known as _______. Answer: elasticity 27) _________ is the ability of a material to resist deformation under stress. Answer: Stiffness 28) The maximum compressive load a material can carry before failure is its _______. Answer: compressive strength 29) The _______ is a measure of how effective a material is in absorbing mechanical energy without sustaining permanent damage. Answer: modulus of resilience 30) Thermal conductance is measured in units of __________. Answer: watts per kelvin (W/K) 31) The opposition to heat current in a material is measured by its __________. Answer: thermal resistance 32) The coefficient of thermal expansion describes how the size of a material changes with a change in __________. Answer: temperature 33) Specific heat capacity is defined as the amount of heat required to raise the temperature of __________ of a substance by one unit. Answer: one kilogram 34) Electrical resistivity is typically expressed in __________. Answer: ohm-meters (Ω⋅m) 35) The dielectric constant of a material measures its ability to store __________. Answer: electrical energy 36) The bending of light rays when they pass from one medium to another is called __________. Answer: refraction 37) When light is absorbed by atoms or molecules, it can cause __________ within the material. Answer: electronic transitions or vibrations 38) The unit for measuring luminous intensity is the __________. Answer: candela 39) In solar energy conversion, light absorption is used to generate electricity in __________ cells. Answer: photovoltaic 40) The ability of a material to allow light to pass through it is measured by its __________. Answer: transmittance 18 41) __________ objects are those that emit their own light, such as the Sun and stars. Answer: Luminous 42) Lightweight metals like aluminum, titanium, and magnesium are commonly used in aerospace applications due to their high __________. Answer: strength-to-weight ratio 43) __________ is a lightweight metal that is approximately one-third the density of steel and is commonly alloyed with copper, magnesium, and zinc. Answer: Aluminum 44) Magnesium, with its silvery white appearance, is lighter than aluminum, with a density of approximately __________. Answer: 1700 kg/m³ 45) Titanium alloys are used in desalination plants due to their excellent __________ resistance. Answer: corrosion 46) The metal that is often used in the production of food packaging materials, such as collapsible tubes and aluminum foil, is __________. Answer: aluminum 47) Aluminum is produced from the ore of __________, which consists mainly of aluminum oxide, silica, clay, and titanium oxide. Answer: bauxite 48) _________ is commonly used for making fan blades and compressor blades in gas turbine engines due to its high strength and temperature resistance. Answer: Titanium 49) Brass is an alloy of copper and _________, while bronze is an alloy of copper and tin. Answer: Zinc 50) Magnesium is often alloyed with _________, manganese, and zinc to improve its mechanical properties. Answer: Aluminum 51) Aluminum has a density that is approximately _________ of the density of steel. Answer: One-third 52) Stainless steels, such as 18/8 stainless steel, contain 18% chromium and 8% _________. Answer: Nickel 53) Pure iron is _________, but adding carbon increases its strength and makes it suitable for structural applications. Answer: Soft 54) Concrete is primarily made up of three main ingredients: ________, ________, and ________. Answer: aggregate, cement, water 55) The ________ of concrete can influence its strength significantly. Answer: water-to-cement ratio 56) Concrete is reinforced with ________ to increase its load-bearing capacity, especially under tensile stress. 19  Answer: steel bars 57) The strength of wood is generally higher when the moisture content is ________. Answer: lower 58) Wood can be classified into two main categories: ________ and ________. Answer: softwood, hardwood 59) The process of adding ________ to concrete helps accelerate curing in cold climates. Answer: calcium chloride 60) Plastics are characterized by being lightweight, strong, and ________. Answer: inexpensive 61) Polymers are the backbone of plastics and have ________ molecular structures. Answer: large, chainlike 62) The application of heat to ________ does not soften the material for remolding. Answer: thermosets 63) Silicon is used extensively in the manufacturing of ________ and electronic chips. Answer: transistors 64) Ordinary glass has a relatively high coefficient of ________ expansion. Answer: thermal 65) The main components of soda-lime-silica glass include sand, ________, and soda ash. Answer: limestone 66) Ceramic materials are non-metallic solids made of ________ compounds. Answer: inorganic 67) The process of making ceramics involves shaping powder and subjecting it to ________. Answer: high temperature 68) The glass fibers used in fiber optics typically have an outer diameter of ________ mm. Answer: 0.0125 69) Composite materials consist of a ________ phase and a fiber phase. Answer: matrix 70) The fibers in composite materials can be oriented in ________ directions to improve strength. Answer: multiple 71 In a composite, if one fiber fails, it does not necessarily lead to failure of ________ or the material as a whole. Answer: other fibers 72) Semiconductors occupy an intermediate position between ________ and ________. Answer: conductors; insulators 73) Common semiconductor materials include Germanium (Ge), Silicon (Si), and ________. Answer: Arsenic (As) 74) The ________ of a semiconductor typically has a negative temperature coefficient of resistance. Answer: resistivity 75) Nuclear fuels such as Uranium (U) and Thorium (Th) are primarily used in ________ engineering applications. 20  Answer: nuclear 76) Moderators in a nuclear reactor are used to ________ neutrons. Answer: slow down 77) Control elements in nuclear reactors are made from materials like ________ or ________. Answer: Boron; Cadmium Descriptive Questions: 1. Explain the importance of selecting appropriate materials for bioengineering applications. Provide at least three factors that must be considered and why they are important. Answer: In bioengineering applications, selecting appropriate materials is crucial because the materials interact directly with the human body. Three critical factors to consider are: Toxicity: The material must be biocompatible and not release harmful substances that can damage tissues or cause adverse reactions. Sterilizability: The material should be able to undergo sterilization processes to prevent infection without degrading in performance. Corrosion Resistance: The material must resist corrosion when in contact with bodily fluids, ensuring the longevity and safety of implants or devices. These considerations ensure that the materials used are safe, durable, and compatible with the body’s environment. 2. Describe how the phase of a material can affect its mechanical and thermophysical properties, using water as an example. Answer: The phase of a material significantly affects its mechanical and thermophysical properties. For example, water exhibits different properties in its solid, liquid, and gaseous states. In its solid form (ice), water is less dense than in its liquid form, which is why ice floats. As water transitions to a gas (steam), its density decreases further, and it becomes much more compressible. Additionally, the temperature of water affects its properties; as temperature increases, the density of liquid water decreases. Therefore, understanding the phase and temperature of a material is crucial when predicting its behavior under different conditions in engineering applications. 3. Explain why thermal expansion is an important property to consider in engineering design. Provide an example of an application where this property plays a crucial role. Answer: Thermal expansion is the tendency of a material to change its dimensions in response to a change in temperature. This is critical in engineering design because materials expand or contract under varying temperatures, which can cause stress, warping, or failure in structures. For example, in bridge construction, engineers must account for the expansion and contraction of metal beams due to temperature fluctuations to prevent structural damage. Expansion joints are often used to accommodate this change. 21 4. What are the key differences between physical, mechanical, and chemical properties of materials? Give examples for each type. Answer: Physical properties are measurable characteristics that describe the state of a physical system without altering its composition. Examples include density, color, and melting point. Mechanical properties describe how a material responds to forces and include strength, ductility, and toughness. These are crucial in determining a material's ability to withstand loads. Chemical properties involve how a material interacts with its environment or other substances. Examples include corrosion resistance, acidity, and atomic bonding. These properties influence how materials degrade or react chemically in certain conditions. 5. Explain why metals are commonly used in cooking utensils in terms of their heat-carrying capacity. Answer: Metals are commonly used in cooking utensils because they have low specific heat capacities, meaning they require less energy to increase their temperature. This property allows them to heat up and cool down quickly, making them ideal for cooking. Additionally, metals have good thermal conductivity, ensuring heat is distributed evenly across the surface, which is important for cooking food efficiently. 6. What is the difference between the melting point and the boiling point of a material? Provide an example to illustrate your explanation. Answer: The melting point is the temperature at which a solid changes into a liquid, while the boiling point is the temperature at which a liquid changes into a gas. For example, water has a melting point of 0°C (where ice turns into liquid water) and a boiling point of 100°C (where liquid water turns into steam). These points differ because the energy required to overcome the forces holding the molecules together is different for the solid-liquid transition compared to the liquid-gas transition. 7. Describe the four types of atomic bonding, providing an example for each type. Answer: Ionic bond: Formed when one atom transfers electrons to another, creating oppositely charged ions that attract each other. Example: Sodium chloride (NaCl). Covalent bond: Involves the sharing of electron pairs between atoms to achieve stability. Example: Water (H₂O). Metallic bond: Occurs when metal atoms share a "sea" of delocalized electrons, allowing them to conduct electricity and heat. Example: Copper (Cu). Hydrogen bond: A weak attraction between a hydrogen atom covalently bonded to an electronegative atom (like O, N, F) and another electronegative atom. Example: Water (H₂O). 8. Explain the concept of corrosion resistance and list some materials known for their high corrosion resistance. Answer: 22 Corrosion resistance refers to the ability of a material to withstand chemical or electrochemical degradation when exposed to environmental factors such as air, moisture, or chemicals. Corrosion can weaken the material’s structural integrity and reduce its useful lifespan. Materials like stainless steel, aluminum, copper, titanium, and nickel are known for their excellent corrosion resistance due to their protective oxide layers or chemical stability in various environments. 9. Explain the difference between tensile strength and compressive strength. Answer: Tensile strength is the maximum stress a material can withstand when being stretched or pulled before breaking, measured by the maximum tensile load per unit area. Compressive strength, on the other hand, is the maximum stress a material can withstand when being compressed or pushed before failure. While tensile strength deals with pulling forces, compressive strength measures a material's ability to resist crushing or compression. 10. Describe the role of ductility and brittleness in material selection for engineering applications. Answer: Ductility and brittleness are critical factors in material selection for engineering applications. Ductile materials, such as mild steel or copper, can deform significantly before fracturing, making them ideal for applications where materials need to be shaped, bent, or stretched, such as in wires or metal forming. Brittle materials, like glass or ceramics, break with little to no deformation, making them suitable for applications where rigidity and hardness are required, such as in cutting tools or structural components. Understanding the ductility or brittleness of a material helps engineers ensure safety, reliability, and performance in various environments and load conditions. 11. Describe the significance of thermal conductance and thermal resistance in engineering applications. Answer: Thermal conductance measures the ability of a material or system to conduct heat, which is crucial in designing heat exchangers, thermally efficient materials, and systems where heat management is critical, such as electronics and buildings. On the other hand, thermal resistance quantifies the opposition to heat flow. High thermal resistance is essential for insulation materials used in buildings and electronics to prevent overheating. By balancing thermal conductance and resistance, engineers can optimize the thermal performance of systems for energy efficiency and safety. 12. Explain the concept of the coefficient of thermal expansion and give examples of how it affects materials in real-life scenarios. Answer: The coefficient of thermal expansion measures how much a material changes in size when its temperature changes. Materials expand when heated and contract when cooled. For example, metal bars in bridges expand during hot days and contract when temperatures drop, which can affect structural integrity. Similarly, balloons shrink in size when exposed to cold temperatures due to the contraction of the material. This property is crucial for engineers to 23 account for expansion and contraction in structures, machinery, and products that undergo temperature variations during use or in different environments. 13. Explain how the refraction of light is used in everyday applications and give two examples. Answer: Refraction of light is used in various everyday applications where light is bent as it passes through different media. This property is essential for devices like eyeglasses and magnifying lenses that help focus light onto the retina for clear vision. It is also used in prisms to separate light into its component colors, as seen in the formation of rainbows. Additionally, refraction is vital in optical fibers for high-speed data transmission. Examples include the use of spectacle lenses to correct vision and the creation of rainbows by water droplets refracting sunlight. 14. Describe the significance of light absorption in solar energy and explain how it is used in solar panels. Answer: Light absorption is crucial in solar energy applications, particularly in solar panels. When sunlight strikes the surface of a solar panel, photons are absorbed by semiconductor materials such as silicon. This absorption of light energy excites electrons, causing them to move and create an electric current. This process, known as the photovoltaic effect, is the basis for generating electricity from sunlight. By maximizing light absorption, solar panels can convert more sunlight into usable electrical energy, making them an essential technology for renewable energy generation. 15. Compare the properties and applications of aluminum and titanium alloys in the aerospace industry. Answer: Aluminum alloys are widely used in aerospace applications because of their low density, good corrosion resistance, and ease of fabrication. They are commonly used for components such as fuselage and wings. However, aluminum alloys cannot withstand extremely high temperatures, which limits their use in engine components. Titanium alloys, on the other hand, have a higher strength-to-weight ratio and excellent resistance to high temperatures (400°C to 600°C), making them ideal for critical components like compressor blades and fan blades in jet engines. While titanium is heavier than aluminum, its strength and temperature resistance make it indispensable in high-performance aerospace applications. Both metals are essential, but their usage depends on the specific demands of different aerospace components. 16. Explain why magnesium is alloyed with elements like aluminum, zinc, and manganese for structural applications. Answer: Pure magnesium is not strong enough for structural applications due to its low mechanical strength. However, when magnesium is alloyed with elements like aluminum, zinc, and manganese, its strength and mechanical properties are significantly enhanced. These alloying elements improve magnesium's resistance to corrosion and increase its tensile strength, making it more suitable for demanding applications such as aerospace components, automobile parts, and sacrificial anodes in corrosion protection. Additionally, magnesium 24 alloys remain lightweight, offering a high strength-to-weight ratio, which is particularly valuable in applications where reducing weight is critical, such as in the automotive and aerospace industries. 17. Explain the properties/characteristics and applications of Iron/steel Properties and Characteristics: Composition: Steel is primarily an alloy of iron (Fe) with a carbon content of approximately 2% or less. The presence of carbon enhances the strength and hardness of iron, making steel a versatile material for various applications. Mechanical Properties: Strength: The addition of carbon significantly increases the tensile strength of steel, making it suitable for structural applications. Ductility: Steel retains good ductility, allowing it to deform without breaking, which is essential in construction and manufacturing. Hardness: Varying carbon content and the addition of other alloying elements can enhance the hardness and wear resistance of steel. Corrosion Resistance: While pure iron is prone to corrosion, alloying with elements such as chromium (in stainless steels) can improve corrosion resistance, making steel suitable for outdoor and marine applications. Types of Steel: Carbon Steels: Contain approximately 0.015 to 2% carbon and are widely used in everyday applications, including construction and manufacturing. Low-Alloy Steels: Contain a maximum of 8% alloying elements and are often used for machine parts and structural components due to their enhanced strength. High-Alloy Steels: Contain more than 8% alloying elements, such as stainless steels, which are known for their corrosion resistance and are commonly used in kitchenware and medical instruments. Applications: Construction: Steel is extensively used in the framework of buildings, bridges, and other infrastructure due to its high strength and durability. Reinforced concrete, which combines steel bars with concrete, is a common structural element in construction. Manufacturing: Steel is used to produce various tools, machinery, and components, including automotive parts, appliances, and industrial equipment, due to its strength and versatility. Appliances: Many household appliances, such as refrigerators, ovens, and washing machines, utilize steel for their structural components because of its strength and affordability. Transportation: Steel is a crucial material in the automotive industry, used for manufacturing car bodies, frames, and components. It is also used in the construction of railways and ships. Toolmaking: High-carbon steels are commonly used to produce cutting tools, drill bits, and other tools that require hardness and wear resistance. Consumer Products: Steel is found in everyday items, including kitchen utensils, furniture, and packaging materials, due to its versatility and ease of fabrication. 25 18. Describe the properties and applications of concrete in construction. Answer: Concrete is a versatile construction material composed of aggregate, cement, and water. Its properties include high compressive strength, which allows it to support heavy loads, while its tensile strength is relatively low, making it brittle under tension. To counteract this weakness, concrete is often reinforced with steel bars, increasing its load-bearing capacity and making it suitable for various structural applications such as roads, bridges, buildings, and tunnels. Additionally, the water-to-cement ratio, type of aggregate, and curing conditions can significantly influence its strength and durability. Precast concrete elements are also popular in construction, allowing for efficient and cost-effective assembly on-site. 19. Explain the classification of wood and its significance in determining strength. Answer: Wood is classified into two primary categories: softwood and hardwood. Softwood comes from coniferous trees, such as pine and spruce, while hardwood comes from deciduous trees, such as oak and maple. This classification is significant because it typically correlates with the wood's density and strength; hardwoods tend to be denser and stronger than softwoods. However, there are exceptions, as some hardwoods can be softer than softwoods. The moisture content and the presence of defects like knots also influence wood's strength. Understanding these classifications helps in selecting the appropriate type of wood for specific applications in construction and manufacturing. 20. Discuss the properties and applications of plastics in modern industries. Answer: Plastics have become essential materials in various industries due to their lightweight, strength, low cost, and versatility in shaping. They are classified mainly into thermoplastics, which can be remolded upon heating, and thermosets, which cannot be reshaped once cured. Common applications include packaging materials, containers, construction materials (like PVC pipes), and consumer products (such as cutlery and disposable items). The demand for durable and inexpensive materials has driven the annual production of plastics to over 100 million metric tons, highlighting their significance in everyday life and industrial applications. 21. Explain the role of silicon in electronics and its significance in manufacturing. Answer: Silicon is a key element in the electronics industry due to its excellent semiconductor properties, allowing it to function as both a conductor and insulator depending on its environment. Pure silicon is not found in nature but is derived from silicon dioxide in sand and combined with other elements. Its ability to manipulate electrical conductivity makes it essential for producing transistors and integrated circuits used in computer chips. Additionally, silicon is alloyed with metals like iron and copper to enhance their properties. Understanding silicon's role is crucial for advancements in technology and manufacturing processes in electronics. 26 22. Discuss the properties and applications of ceramic materials in modern technology. Answer: Ceramic materials are non-metallic solids characterized by their exceptional electrical, thermal, and chemical properties. Commonly made from inorganic compounds such as oxides and nitrides, ceramics are fabricated through a process of shaping powder and applying high temperatures to achieve a compact form. These materials are widely used in electronic control devices, aerospace components, and nuclear engineering due to their durability and resistance to extreme conditions. Examples of ceramics include aluminum oxide (Al2O3), magnesium oxide (MgO), and various types of glass. Their unique properties make ceramics ideal for applications requiring high strength and stability, particularly in harsh environments. 23. Explain the composition and benefits of composite materials, highlighting their significance in aerospace applications. Answer: Composite materials consist of two primary phases: a matrix and reinforcing fibers. The matrix, typically a polymer, metal, or ceramic, provides ductility and support, while the fibers—such as glass, carbon, or silicon carbide—offer high strength and rigidity. The combination of these materials creates a new material with superior properties, such as increased strength-to-weight ratios and enhanced resistance to failure. In aerospace applications, these benefits are crucial, as lighter materials contribute to fuel efficiency and overall performance. Composites are used in various aerospace components, including military aircraft, satellites, and commercial airplanes, where their ability to withstand multidirectional loads and minimize weight is particularly advantageous. 24. Describe the properties of semiconductors and their applications in modern technology. Answer: Semiconductors are solid materials that allow the passage of electrons under certain conditions, making them crucial for various electronic applications. They typically exhibit high resistivity and a negative temperature coefficient of resistance, meaning their conductivity increases with temperature. Common examples include silicon, germanium, and arsenic. Semiconductors are integral in devices such as transistors, diodes, rectifiers, and photocells, which are essential in telecommunications, computing, and power engineering. Their unique properties enable advancements in miniaturization and efficiency in electronic circuits, impacting modern technology significantly. 25. Explain the role of various materials used in nuclear engineering applications, specifically focusing on nuclear fuels and their functionalities. Answer: In nuclear engineering, specific materials serve critical roles in the functioning of reactors. Nuclear fuels such as Uranium, Thorium, and Plutonium are used to generate energy through fission reactions. Moderators, like water or graphite, slow down neutrons, enhancing the likelihood of fission. Control elements, typically made of Boron or Cadmium, help regulate the fission process by absorbing excess neutrons. Fuel canning materials ensure that the nuclear fuel is contained safely, while reflectors and pressure vessel materials enhance the 27 efficiency and safety of the reactor. These materials collectively contribute to the controlled release of energy and the overall safety of nuclear power generation. 26. What are the classification of Engineering Materials Match the Following Type 01. Given the Following, match the correct answer: a) State of matter with fixed volume and 1 Solids shape 2 Liquids b) Resistance to material degradation 3 Gases c) Molecules far apart, high compressibility 4 Plasma d) No fixed shape but fixed volume 5 Density e) Free electrons and nuclei 6 Corrosion Resistance f) Property that changes with temperature g) Electrical conductivity h) Phase change from solid to liquid 1 → a) 2 → d) 3 → c) 4 → e) 5 → f) 6 → b) 02. Given the Following, match the correct answer: 1 Water molecules a) Ability to transfer heat 2 Thermal conductivity b) H2O Design engineer's 3 question c) Stress-strain behavior 4 Material's load response d) Can be easily cut or shaped 5 Machinability e) Ultimate strength 6 Solid ice f) Melting point of 0°C g) Atomic bonding h) Resistance to electricity 1 → b) 2 → a) 3 → e) 4 → c) 5 → d) 6 → f) 28 03. Given the Following, match the correct answer: 1 Ultimate strength a) Atomic bonding 2 Free electrons b) Deformation limit under load 3 Acidity or Alkalinity c) Easily shaped or cut 4 Machinability d) pH scale measurement 5 Plasma state e) State of matter beyond gas Temperature 6 dependence f) Affects density g) Electrical conductor h) Melting point 0°C 1 → b) 2 → g) 3 → d) 4 → c) 5 → e) 6 → f) 04. Given the Following, match the correct answer: 1 Corrosion a) Material’s ability to resist rusting 2 Electrical insulation b) Atoms spread apart, high compressibility 3 Chemical composition c) No fixed shape, definite volume 4 Liquids d) Prevents electricity flow 5 Gases e) Changes with temperature 6 Thermal expansion f) Periodic table elements g) Heat transfer ability h) Molecules packed tightly 1 → a) 2 → d) 3 → f) 4 → c) 5 → b) 6 → e) 29