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Unit 3: Nanomaterials and Composites - Practice Quiz

CHE124 — Engineering Chemistry 60 Questions
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1 Nanomaterials are materials that have at least one dimension in the size range of:

introduction to nanomaterials Easy
A. 1 to 100 m
B. 100 to 500 nm
C. 1 to 100 nm
D. 1 to 100 mm

2 As particle size decreases to the nanoscale, the surface area to volume ratio:

introduction to nanomaterials Easy
A. Increases
B. Becomes zero
C. Remains constant
D. Decreases

3 A quantum dot, in which all three dimensions are at the nanoscale, is classified as which type of nanomaterial?

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Easy
A. 2D
B. 0D
C. 3D
D. 1D

4 Nanowires and nanotubes, which have two dimensions at the nanoscale and one that is larger, are classified as:

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Easy
A. 1D
B. 0D
C. 3D
D. 2D

5 Graphene, a single sheet with only its thickness at the nanoscale, is an example of a:

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Easy
A. 1D nanomaterial
B. 0D nanomaterial
C. 2D nanomaterial
D. 3D nanomaterial

6 The fullerene commonly known as a buckyball has the chemical formula:

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Easy
A.
B.
C.
D.

7 Graphene consists of carbon atoms arranged in a:

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Easy
A. Single-layer honeycomb lattice
B. Body-centered lattice
C. Cubic crystal lattice
D. Random amorphous network

8 A carbon nanotube can be visualized as which of the following?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Easy
A. A stacked pile of fullerenes
B. A diamond crystal wire
C. A rolled-up sheet of graphene
D. A chain of individual atoms

9 The change in properties of nanomaterials as their size decreases is referred to as:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Easy
A. Density effect
B. Thermal drift
C. Size-dependent effect
D. Bulk effect

10 Gold nanoparticles often appear red rather than the golden color of bulk gold. This is an example of a size-dependent:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Easy
A. Acoustic property
B. Optical property
C. Thermal property
D. Magnetic property

11 Breaking down bulk material into nanoscale particles is characteristic of which synthesis approach?

methods of nanomaterial synthesis: top-down and bottom-up approaches Easy
A. Self-assembly
B. Sol-gel
C. Bottom-up
D. Top-down

12 Building nanomaterials by assembling atoms or molecules together is known as the:

methods of nanomaterial synthesis: top-down and bottom-up approaches Easy
A. Top-down approach
B. Ball milling approach
C. Bottom-up approach
D. Etching approach

13 Which of the following is an example of a top-down synthesis method?

methods of nanomaterial synthesis: top-down and bottom-up approaches Easy
A. Ball milling
B. Self-assembly
C. Sol-gel process
D. Chemical vapor deposition

14 Nanomaterials are effective catalysts mainly because they provide:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Easy
A. A lower melting point
B. Higher electrical resistance
C. A large surface area
D. Reduced reactivity

15 In the biomedical field, nanomaterials are widely used for:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Easy
A. Making cement
B. Road construction
C. Water pipe insulation
D. Targeted drug delivery

16 Nanomaterials are used in energy technologies such as supercapacitors mainly to improve:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Easy
A. Charge storage capacity
B. Material weight
C. Corrosion rate
D. Manufacturing cost

17 A composite material is made by combining:

fundamental concepts of composite materials Easy
A. Two identical metals
B. A single pure element
C. Only gases
D. Two or more distinct materials

18 In a composite material, the continuous phase that holds the reinforcement together is called the:

role of matrix and reinforcement, composition, structure, and characteristic properties of composites Easy
A. Matrix
B. Filler particle
C. Reinforcement
D. Fiber

19 A composite reinforced with long strands of glass or carbon is classified as a:

classification of composites based on reinforcement type, including particulate composites, fiber-reinforced composites, and structural composites Easy
A. Metal matrix composite
B. Particulate composite
C. Fiber-reinforced composite
D. Laminar composite

20 Fiber-reinforced composites are widely used in the aerospace industry mainly because they are:

Engineering applications of composites Easy
A. Heavy and brittle
B. Soft and elastic
C. Strong and lightweight
D. Cheap and dense

21 A material is generally classified as a nanomaterial when at least one of its dimensions falls in the range of:

introduction to nanomaterials Medium
A. – nm
B. – nm
C. – m
D. – mm

22 The dramatic change in properties of nanomaterials compared to bulk materials is primarily attributed to:

introduction to nanomaterials Medium
A. Higher melting point of the bulk phase
B. Reduced number of atoms per unit cell
C. Increased density of the material
D. High surface-area-to-volume ratio and quantum effects

23 A quantum dot with all three dimensions confined to the nanoscale is classified as:

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Medium
A. 1D nanomaterial
B. 3D nanomaterial
C. 0D nanomaterial
D. 2D nanomaterial

24 A nanowire has two dimensions confined to the nanoscale while one dimension is extended. It is therefore a:

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Medium
A. 1D nanomaterial
B. 3D nanomaterial
C. 0D nanomaterial
D. 2D nanomaterial

25 Graphene is best classified under which dimensional category of nanomaterials?

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Medium
A. 1D nanomaterial
B. 0D nanomaterial
C. 3D nanomaterial
D. 2D nanomaterial

26 The fullerene (buckyball) consists of carbon atoms arranged as:

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Medium
A. hexagons only
B. pentagons only
C. hexagons and pentagons
D. hexagons and pentagons

27 In graphene, each carbon atom is bonded to three neighbors using which hybridization?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Medium
A.
B.
C.
D.

28 Whether a single-walled carbon nanotube behaves as a metal or a semiconductor is primarily determined by its:

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Medium
A. Color under light
B. Chirality (rolling angle)
C. Purity of synthesis
D. Length

29 When the size of a semiconductor nanoparticle decreases, its band gap generally:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Medium
A. Decreases due to quantum confinement
B. Increases due to quantum confinement
C. Becomes zero
D. Remains constant

30 Gold nanoparticles appear ruby red in colloidal solution rather than golden due to:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Medium
A. Oxidation to gold oxide
B. Change in atomic number
C. Surface plasmon resonance
D. Increased density of gold

31 The melting point of a metal nanoparticle compared to its bulk value typically:

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Medium
A. Decreases as size decreases
B. Doubles at the nanoscale
C. Increases as size decreases
D. Stays exactly the same

32 Which of the following is a top-down method of nanomaterial synthesis?

methods of nanomaterial synthesis: top-down and bottom-up approaches Medium
A. Chemical vapour deposition
B. Self-assembly of molecules
C. Sol-gel process
D. Ball milling

33 The sol-gel and chemical vapour deposition methods are examples of which synthesis approach?

methods of nanomaterial synthesis: top-down and bottom-up approaches Medium
A. Lithographic etching approach
B. Top-down approach
C. Mechanical grinding approach
D. Bottom-up approach

34 A key advantage of bottom-up synthesis over top-down methods is:

methods of nanomaterial synthesis: top-down and bottom-up approaches Medium
A. Inability to form ordered structures
B. Better control over size and uniformity of nanostructures
C. Higher production of surface defects
D. Requirement of only bulk raw material

35 Nanomaterials greatly enhance catalytic activity mainly because they provide:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Medium
A. A larger active surface area per unit mass
B. A lower number of active sites
C. A thicker diffusion barrier
D. A higher melting point for reactions

36 In targeted drug delivery, nanoparticles are especially useful because they can:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Medium
A. Carry drugs to specific cells and release them in a controlled way
B. Dissolve only in metallic tissues
C. Increase the drug's molecular weight for stability
D. Convert drugs into inert gases

37 Nanostructured electrodes improve supercapacitor performance primarily by:

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Medium
A. Reducing the operating voltage window
B. Eliminating the need for an electrolyte
C. Blocking ion movement in the electrolyte
D. Increasing surface area for charge storage

38 A composite material is best defined as:

fundamental concepts of composite materials Medium
A. A pure element refined to nanoscale purity
B. A single-phase alloy of two metals
C. A combination of two or more distinct materials with a recognizable interface
D. A homogeneous solution of two liquids

39 In a fiber-reinforced composite, the primary role of the matrix is to:

role of matrix and reinforcement Medium
A. Provide the composite's electrical conductivity
B. Act as the sole strengthening phase
C. Bind fibers together and transfer load to them
D. Carry most of the applied load directly

40 In most fiber-reinforced composites, the reinforcement phase mainly provides:

role of matrix and reinforcement Medium
A. Electrical grounding only
B. Strength and stiffness
C. Thermal insulation only
D. Corrosion resistance only

41 A material is described as having all three of its external dimensions above the nanoscale, but it is composed internally of nanoscale grains, layers, or clusters. How should this material be classified and why?

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Hard
A. 2D nanomaterial, because layered internal features dominate its behavior
B. 3D nanomaterial, because bulk dimensions exceed 100 nm while nanoscale features exist internally
C. 0D nanomaterial, because the internal clusters are quantum dots
D. 1D nanomaterial, because the grains align into nanoscale channels

42 For a semiconductor quantum dot, the effective band gap increases as particle size decreases. If the confinement energy scales approximately as where is the diameter, reducing the diameter from to changes the confinement contribution by what factor?

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Hard
A. Decreases by a factor of
B. Increases by a factor of
C. Increases by a factor of
D. Increases by a factor of

43 A single-walled carbon nanotube is defined by chiral indices . Which condition determines whether the nanotube behaves as a metallic conductor?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Hard
A. only (armchair) with no other cases
B. is a multiple of
C. is even
D. is a multiple of

44 In (buckminsterfullerene), the structure consists of 12 pentagons and 20 hexagons. Using Euler's rule for a closed cage of carbons, why must exactly 12 pentagons be present regardless of the number of hexagons?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Hard
A. Euler's polyhedron formula fixes pentagons at 12 to close the cage independent of hexagon count
B. Pentagons must equal the number of vertices divided by 5
C. The number of pentagons equals half the number of hexagons
D. Hexagons alone can close a cage, so 12 pentagons is arbitrary

45 A researcher needs monodisperse nanoparticles with atomically precise control over composition and minimal defects. Which pairing of approach and reasoning is most appropriate?

methods of nanomaterial synthesis: top-down and bottom-up approaches Hard
A. Top-down, because milling gives precise atomic control
B. Top-down, because lithography avoids all surface defects
C. Bottom-up, because it always produces larger particles faster
D. Bottom-up, because assembly from atoms/molecules allows fine control over size and structure

46 The fraction of atoms on the surface of a nanoparticle rises sharply as size decreases. This surface-to-volume effect most directly explains which observed behavior?

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Hard
A. Constant catalytic activity irrespective of size
B. Increase in the melting point above the bulk value
C. Complete loss of crystallinity in all nanoparticles
D. Depression of the melting point compared to the bulk material

47 Gold nanoparticles appear ruby-red in colloidal suspension rather than golden. Which phenomenon is chiefly responsible for this size-dependent optical behavior?

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Hard
A. Fluorescence from d-band transitions
B. Total internal reflection within each particle
C. Localized surface plasmon resonance absorbing green light
D. Rayleigh scattering of blue light only

48 Nanostructured electrodes greatly boost supercapacitor performance mainly because of which combined effect?

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Hard
A. Reduced surface area concentrates charge at fewer sites
B. High surface area increases charge storage while short diffusion paths speed ion transport
C. Larger grain size increases Faradaic reactions and lowers resistance
D. Increased electrode thickness shortens the electrolyte path

49 For a continuous fiber-reinforced composite loaded parallel to the fibers (isostrain condition), the longitudinal modulus follows the rule of mixtures. If , , and fiber volume fraction , what is ?

fundamental concepts of composite materials Hard
A.
B.
C.
D.

50 In a fiber-reinforced composite under longitudinal tension, what is the primary mechanical role of the matrix phase?

role of matrix and reinforcement Hard
A. Providing the highest stiffness in the composite
B. Acting as the main crack-initiation site by design
C. Transferring applied load to the fibers via shear and protecting them
D. Carrying the majority of the tensile load directly

51 A continuous fiber composite is loaded transverse to the fibers (isostress condition). Using the inverse rule of mixtures with , , , the transverse modulus is closest to which value?

fundamental concepts of composite materials Hard
A.
B.
C.
D.

52 A sandwich panel with stiff face sheets bonded to a lightweight honeycomb core is best classified as which type of composite, and what governs its bending stiffness?

classification of composites based on reinforcement type, including particulate composites, fiber-reinforced composites, and structural composites Hard
A. Particulate composite; stiffness set by particle volume fraction
B. Dispersion-strengthened composite; stiffness set by dispersoid size
C. Fiber-reinforced composite; stiffness set by fiber orientation
D. Structural composite; bending stiffness rises with face-sheet separation by the core

53 Why do nanoparticle catalysts often show far higher activity per unit mass than their bulk counterparts?

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Hard
A. Bulk atoms in the interior are the dominant catalytic sites
B. A high fraction of low-coordination surface atoms provides abundant active sites
C. Smaller particles reduce the total surface area exposed to reactants
D. Nanoparticles eliminate the need for reactant adsorption

54 Graphene exhibits extremely high charge-carrier mobility. Which feature of its electronic structure is most directly responsible for its charge carriers behaving as massless Dirac fermions?

carbon-based nanomaterials including fullerenes (buckyballs), carbon nanotubes, and graphene Hard
A. Localized flat bands across the Brillouin zone
B. Linear energy-momentum dispersion at the Dirac points where bands touch
C. Strong ionic bonding between carbon layers
D. A large parabolic band gap at the K points

55 Chemical vapor deposition (CVD) is widely used to grow high-quality graphene and carbon nanotubes. Which classification and rationale correctly describe CVD?

methods of nanomaterial synthesis: top-down and bottom-up approaches Hard
A. Bottom-up, because solid material is assembled from gas-phase precursor molecules
B. Top-down, because a bulk carbon block is etched into sheets
C. Bottom-up, because it grinds precursors into fine powder
D. Top-down, because it relies on mechanical exfoliation

56 A nanowire and a graphene sheet differ in how many dimensions are confined to the nanoscale. Which statement correctly pairs each with its dimensional class?

classification of nanomaterials based on dimensionality (0D, 1D, 2D, and 3D) Hard
A. Nanowire is 0D; graphene is 3D
B. Both are 0D because carriers are fully confined
C. Nanowire is 1D (two dimensions confined); graphene is 2D (one dimension confined)
D. Nanowire is 2D; graphene is 1D

57 In targeted drug delivery, nanoparticles can accumulate preferentially in tumor tissue even without active targeting ligands. Which effect explains this passive accumulation?

applications of nanomaterials in catalysis, electronics and telecommunication, biomedical and pharmaceutical fields, and energy-related technologies such as batteries, supercapacitors, and solar cells Hard
A. Covalent bonding of nanoparticles to healthy tissue only
B. Active transport by tumor-cell ion pumps selecting nanoparticles
C. Enhanced permeability and retention due to leaky tumor vasculature and poor lymphatic drainage
D. Magnetic attraction of all nanoparticles to cancer cells

58 A designer wants a composite with high specific strength (strength-to-weight ratio) for aerospace panels. Comparing options, why is a carbon-fiber/epoxy composite generally preferred over a steel component of equal strength?

composition, structure, and characteristic properties of composites Hard
A. Its low density gives higher strength-to-weight ratio at comparable strength
B. Its metallic matrix conducts heat better than steel
C. Its isotropic behavior guarantees equal properties in all directions
D. Its higher density improves fatigue resistance directly

59 Individual defect-free carbon nanotubes show very high thermal conductivity, yet bulk mats of nanotubes conduct heat poorly. What primarily accounts for this discrepancy?

electronic, optical, mechanical, and thermal properties of nanomaterials with size-dependent effects Hard
A. Electron scattering replacing phonon transport in mats
B. Complete loss of the crystalline structure upon bundling
C. A drop in intrinsic conductivity of each tube when bundled
D. Phonon scattering at tube-tube junctions and interfacial thermal resistance in the mat

60 Fiber-reinforced polymer (FRP) bars are increasingly used instead of steel rebar in bridge decks exposed to de-icing salts. Which property advantage most directly justifies this choice?

Engineering applications of composites Hard
A. Higher thermal conductivity to melt ice on the deck
B. Higher ductility than steel allowing large plastic deformation
C. Corrosion resistance, since FRP does not rust like steel in chloride environments
D. Magnetic behavior that repels salt ions
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