The Ultimate Materials Science Practice Test!

The explanation for the given answer is that malleability refers to the ability of a material to be shaped or formed into thin sheets by applying pressure, such as rolling or hammering. This property is commonly observed in materials like metals, which can be easily flattened into sheets without breaking or cracking. Therefore, it is correct to agree that malleability is the property of a material that allows it to be rolled or hammered into thin sheets.

The given statement is correct. In a crystalline material, atoms are arranged in a definite and orderly manner, forming a crystal lattice structure. This regular arrangement of atoms gives rise to the characteristic properties of crystalline materials, such as their geometric shape, cleavage planes, and optical properties. The arrangement of atoms in a crystal lattice is highly organized and repetitive, leading to the formation of well-defined crystal structures.

In a body centred cubic space lattice, there are nine atoms. This is because there are eight atoms located at the corners of the cube and one atom at its centre. Therefore, the statement is true and the answer is "Yes".

The face-centered cubic space lattice is a type of crystal structure that is found in various metals, including gamma-iron, aluminum, copper, lead, silver, and nickel. This lattice structure is characterized by atoms located at the corners of a cube and additional atoms located at the center of each face of the cube. Therefore, the statement that the face-centered cubic space lattice is found in these metals is true.

The statement is true because stiffness refers to the ability of a material to resist deformation when subjected to stress. A material with high stiffness will resist bending or stretching when a force is applied to it, while a material with low stiffness will deform more easily. Therefore, the statement accurately describes the concept of stiffness.

The correct answer is (A) hexagonal close packed lattice. Hexagonal close packed (HCP) lattice has the highest packing of atoms among the given options. In an HCP lattice, the atoms are arranged in a close-packed manner with each atom surrounded by 12 nearest neighbors. This arrangement maximizes the number of atoms that can be packed together in a given space, resulting in the highest packing efficiency. Body central cubic lattice and simple cubic lattice have lower packing efficiencies compared to HCP lattice. Therefore, the HCP lattice is the correct answer.

Brittle materials are characterized by their lack of ductility, which means they do not undergo significant elongation or deformation when subjected to tensile loads. Instead, they tend to fracture or snap off abruptly without any noticeable elongation. Therefore, the statement is true, and the correct answer is A. Yes.

Malleability refers to the ability of a material to be rolled or hammered into thin sheets without breaking or cracking. This property allows the material to be easily shaped and formed into various shapes and sizes. Option D correctly identifies this characteristic of malleability, making it the correct answer.

In Brinell hardness testing, the timer for loading is set to 15 seconds. This means that the test material is subjected to a specific load for a duration of 15 seconds. This loading time is important because it allows for the proper indentation to be made on the material's surface, which is then measured to determine its hardness. A shorter loading time may not provide enough pressure for a clear indentation, while a longer loading time may result in excessive deformation of the material. Therefore, a loading time of 15 seconds is considered appropriate for accurate Brinell hardness testing.

Ductility is the property of a material that allows it to be stretched or drawn into wires without breaking. This means that the material can be elongated under tensile stress without losing its strength or fracturing. Therefore, option A is the correct answer because it accurately describes the property of ductility.

The correct answer is C. can cut another metal. Hardness is a measure of a material's resistance to deformation, particularly when it comes to scratching or cutting. A material that is hard will be able to cut or scratch another material that is softer than it. Therefore, the property of hardness allows a material to cut another metal.

Plasticity is the property of a material that allows it to retain deformation permanently. This means that when a material is subjected to a force or stress, it can be permanently reshaped or deformed without returning to its original shape. Plasticity is often associated with materials that can be molded or shaped easily, such as clay or metals. This property is different from ductility and malleability, which refer to the ability of a material to be stretched or bent without breaking.

Ductility is the property of a material that allows it to be stretched or drawn into a wire without breaking. This property is particularly important for metals, as it allows them to be easily formed into different shapes and sizes. Malleability, on the other hand, refers to the ability of a material to be deformed under compression, while plastic deformation and elastic deformation are general terms that describe the behavior of materials under stress. Straining is not a specific property related to the ability of metals to be drawn into wire.

The correct answer is C. can cut another metal. Hardness refers to the ability of a material to resist deformation, particularly when it comes into contact with another material. A material with high hardness can cut or scratch another material with lower hardness. This is because the hard material is able to exert a greater force on the softer material, causing it to deform or break. Therefore, the ability to cut another metal is a characteristic of a material with high hardness.

In a body-centered cubic (BCC) unit cell, there is one atom at each of the eight corners and one atom in the center of the cube. This adds up to a total of nine atoms in the unit cell.

Brittleness is the property of a material where it breaks easily with little permanent distortion. This means that when a brittle material is subjected to stress, it fractures without undergoing significant deformation. It is the opposite of ductility and malleability, where materials can be stretched or bent without breaking. Plasticity refers to the ability of a material to undergo permanent deformation without breaking, which is not the case with brittle materials. Therefore, the correct answer is A. brittleness.

Ductility refers to the ability of a material to undergo significant permanent deformation when subjected to a tensile force. This means that the material can stretch and elongate without breaking or fracturing. Therefore, the statement that the ability of a material to undergo large permanent deformation with the application of a tensile force is called ductility is correct.

The machinability of a metal refers to how easily it can be machined or shaped using various cutting tools. Hardness and tensile strength are two important factors that influence machinability. A metal with high hardness may be difficult to cut or shape, while a metal with high tensile strength may cause excessive tool wear. Therefore, both hardness and tensile strength play a significant role in determining the machinability of a metal.

Both nitric acid and picric acid can be used as etching reagents for carbon steels. Nitric acid is commonly used for general etching of carbon steels, while picric acid is often used for revealing grain boundaries and other microstructural features. Therefore, the correct answer is c. Both a. and b.

Toughness is a desirable property in parts subjected to shock and impact loads because it measures a material's ability to absorb energy and deform plastically before fracturing. A tough material can withstand sudden forces without breaking or shattering. Strength alone may not be sufficient as a brittle material with high strength can easily fracture under impact loads. Stiffness is related to a material's resistance to deformation and is not directly related to its ability to absorb energy. Brittleness refers to a material's tendency to fracture without significant plastic deformation, making it unsuitable for shock and impact loads.

The correct answer is D. all of the above. This means that all of the statements A, B, and C are true. Statement A explains that unit cells contain the smallest number of atoms that have all the properties of the crystals of a specific metal. Statement B states that unit cells have the same orientation and their similar faces are parallel. Statement C defines unit cells as the smallest parallelepiped that can be transposed in three coordinate directions to build up the space lattice. Since all three statements are true, the correct answer is D. all of the above.

Glass is an amorphous material because it lacks a crystalline structure. Unlike mica, silver, and lead, which have a definite arrangement of atoms, glass has a disordered arrangement of atoms. This lack of long-range order gives glass its unique properties, such as transparency and the ability to be molded into various shapes.

Magnesium has a hexagonal close packed (HCP) structure. In this structure, the atoms are arranged in a hexagonal pattern with each atom surrounded by six nearest neighbors. This arrangement allows for efficient packing of atoms, resulting in a dense and stable structure. Silver, iron, and aluminum do not have a hexagonal close packed structure.

The study of metallography involves examining the structure and composition of metals and alloys. This includes analyzing alloy constituents, conducting failure analysis to understand the reasons for material failure, and studying the metal structure to determine its properties and behavior. Therefore, option d, "all of the above," is the correct answer as it encompasses all the aspects mentioned in the question.

Metallic solids are malleable and ductile because they consist of a lattice of positive metal ions surrounded by a sea of delocalized electrons. This arrangement allows the metal atoms to easily slide past each other without breaking bonds, making them malleable. The delocalized electrons also contribute to the ductility of metallic solids by allowing the metal to be stretched into wires without breaking. Ionic solids, on the other hand, are brittle and not malleable or ductile because they consist of a lattice of positive and negative ions held together by strong electrostatic forces, which are easily disrupted when the solid is deformed. Covalent solids also tend to be brittle and not malleable or ductile due to the strong covalent bonds between atoms.

The indenter used in Vickers hardness testing machine is a diamond square-based pyramid. This type of indenter is commonly used in Vickers hardness testing because it provides a more accurate and precise measurement of hardness. The diamond indenter creates a square-shaped indentation on the material being tested, and the size of this indentation is used to calculate the hardness value. The diamond indenter is preferred over other options like ball indenters because it is harder and can be used to test a wider range of materials.

Platinum is considered a noble metal because it is resistant to corrosion and oxidation. It is also known for its high melting point and durability. These properties make it highly valuable and useful in various industries, including jewelry, electronics, and automotive.

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The property of resilience is essential for spring materials because it refers to the ability of a material to absorb and store energy when it is deformed, and then release that energy when the deforming force is removed. This is crucial for springs as they need to be able to withstand repeated deformation without permanent damage or deformation. Stiffness refers to the ability of a material to resist deformation, ductility refers to the ability to be stretched without breaking, and plasticity refers to the ability to permanently deform without breaking. While these properties may be important for other materials or applications, resilience is specifically important for spring materials.

Toughness refers to the ability of a material to resist fracture under high impact loads. It is a measure of how much energy a material can absorb before breaking. A material with high toughness can withstand sudden shocks and impacts without fracturing, while a material with low toughness is more likely to break under such conditions. Therefore, toughness is the correct answer in this case.

The word "elastic" refers to something that is flexible and can stretch or rebound easily. The opposite of this would be something that is not flexible and cannot easily stretch or rebound, which is the definition of "rigid". Therefore, "rigid" is the correct opposite of "elastic".

Creep is the correct answer because it refers to the slow plastic deformation of metals under a constant stress. This phenomenon occurs over time and at elevated temperatures, causing the material to gradually deform under the applied stress. Creep can lead to structural failure if not properly accounted for in engineering design.

The correct answer is (C) Body centered cubic. Body centered cubic (BCC) is a crystal structure in which each atom is surrounded by eight neighboring atoms, with one atom located at the center of the unit cell. This structure is commonly found in metals such as iron. Simple Cubic (A) has atoms located only at the corners of the unit cell, Face centered cubic (B) has atoms located at the corners and center of each face of the unit cell, and Close packed hexagonal (D) has a hexagonal arrangement of atoms with a close-packed layer and a second layer directly above it.

Most of the common metals have a cubic crystal structure. This means that the atoms are arranged in a regular, repeating pattern with equal distances between them in all directions. The cubic structure can be further classified into three types: face-centered cubic (FCC), body-centered cubic (BCC), and simple cubic (SC). In the FCC structure, there is an atom at each corner of the unit cell and one in the center of each face. In the BCC structure, there is an atom at each corner and one in the center of the unit cell. The SC structure has an atom at each corner only. Since the question does not specify which type of cubic structure, the correct answer is "Cubic".

The hardness of a material enables it to resist abrasion, penetration, and plastic deformation. When a material is hard, it is less likely to be scratched or worn away by rubbing or friction (abrasion). It is also less likely to be pierced or penetrated by a sharp object (penetration). Additionally, a hard material is less likely to undergo permanent deformation when subjected to a load or force (plastic deformation). Therefore, all of the above options are correct.

Closed packed hexagonal space lattice refers to a crystal structure in which the atoms are arranged in a close-packed hexagonal pattern. This arrangement is found in zinc, magnesium, cobalt, cadmium, antimony, and bismuth. These elements have a similar atomic radius and bonding characteristics that allow them to form a hexagonal lattice structure. Gamma-iron, aluminium, copper, lead, silver, nickel, alpha-iron, tungsten, chromium, and molybdenum do not have this specific lattice structure.

The coordination number of a face centered cubic space lattice is twelve because each atom in the lattice is surrounded by twelve nearest neighbors. This is because each face of the unit cell has one atom at its center, and each corner of the unit cell is shared by eight adjacent unit cells. Therefore, each atom has six nearest neighbors in its own unit cell and an additional six nearest neighbors in the adjacent unit cells, resulting in a total of twelve nearest neighbors.

To observe the grain size of steel samples under a microscope, a higher magnification is required. A magnification of 100x would provide a clear and detailed view of the grains. Lower magnifications such as 2x or 10x would not provide enough detail to accurately observe the grain structure, while higher magnifications such as 1500x would be excessive and may result in a distorted image. Therefore, a magnification of 100x is the most suitable option for observing the grain size of steel samples under a microscope.

In a face centred cubic (FCC) space lattice, each corner of the unit cell is occupied by an atom, and there is an additional atom at the center of each face. This means that there are a total of 8 corner atoms and 6 face atoms in the unit cell. Therefore, the total number of atoms in a unit cell of a face centred cubic space lattice is 8 + 6 = 14.

The body-centered cubic (BCC) space lattice is characterized by a lattice structure in which each lattice point is surrounded by eight neighboring lattice points, forming a cube. This type of lattice is found in alpha-iron, tungsten, chromium, and molybdenum. Zinc, magnesium, cobalt, cadmium, antimony, bismuth, gamma-iron, aluminum, copper, lead, silver, and nickel do not have a body-centered cubic lattice structure.

A face-centered cubic (FCC) space lattice is a type of crystal structure in which the lattice points are located at the corners and centers of each face of the unit cell. In an FCC lattice, there are 4 atoms located at each of the corners of the unit cell and 1 atom located at the center of each face. Therefore, the total number of atoms in a unit cell of an FCC lattice is 4 + 1 = 5. Since the given answer states that there are 14 atoms in a unit cell, it is not correct.

Tin has the lowest melting point compared to the other metals listed. This means that it requires the least amount of heat to change from a solid to a liquid state. Antimony, silver, and zinc all have higher melting points than tin.

In Brinell hardness testing, the minimum thickness of the specimen should be more than 10 times the depth of impression. This requirement ensures that the specimen is thick enough to prevent any deformation or distortion caused by the impression. If the specimen is too thin, it may result in inaccurate hardness measurements as the material may not be able to withstand the indentation force without deforming. Therefore, a minimum thickness greater than 10 times the depth of impression is necessary to ensure reliable and accurate hardness measurements.

The correct answer is B) Alpha iron. Alpha iron, also known as ferrite, has a body-centered cubic (BCC) structure, not a hexagonal close packed (HCP) structure. Magnesium, titanium, zinc, and cadmium all have HCP structures.

A carbon steel with a Brinell hardness number of 100 indicates that it has a relatively low hardness. Hardness is often correlated with the strength of a material, so a carbon steel with a lower hardness would generally have a lower ultimate tensile strength. Therefore, the ultimate tensile strength of this carbon steel would be closer to 350 N/mm2, which is the value given in option C.

Molybdenum has a body-centered cubic (BCC) structure. In this structure, each atom is located at the center of a cube, with eight atoms at the corners and one atom in the center of the cube. Molybdenum's BCC structure gives it certain properties, such as high melting point and good strength at high temperatures.

Nitriding is a surface hardening process in which nitrogen is diffused into the surface of a metal to increase its hardness and wear resistance. The Brinell hardness scale measures the hardness of a material by indenting a spherical indenter into the surface of the material and measuring the diameter of the resulting indentation. Nitrided surfaces typically have a very high hardness, often exceeding 600 on the Brinell hardness scale. Therefore, the correct answer is E) More than 600.

Brass is an alloy made primarily of copper and zinc. The crystal structure of brass is face-centered cubic (FCC), which means that the atoms are arranged in a cubic lattice with additional atoms located at the center of each face. This arrangement allows for close packing of atoms and results in a relatively dense and stable structure.

Tin does not have a face centred cubic structure.