Biomaterial Test 2 Practice Problem
Carbon nanotubes and graphite can be toxic due to: a. Hydrophobicity b. Small size c. Chemical reactivity d. All of the above
d. All of the above
Carbon nanotubes and graphite can: a. Improve mechanical strength b. Induce slow but significant degradation c. Improve thermal and electrical conductivity d. All of the above
d. All of the above
Which of the following is TRUE about CNTs: a. C is sp^2 hybridized b. C atoms are arranged in a hexagonal lattice c. Rolled graphene sheets d. All of the above
d. All of the above
Describe the difference between isotropes and allotropes?
isotropes- same properties, in one direction allotropes- same material but different crystal structure
The dependent permanent deformation is called _________________. (a) Plastic deformation (b) Elastic deformation (c) Creep (d) inelastic deformation
(c) Creep
If a material is subjected to two incremental true strains namely E^1 and E^2 , then the total true strain is (a) E^1 * E^2 (b) E^1 - E^2 (c) E^1 + E^2 (d) E^1 / E^2
(c) E^1 + E^2
Yield point may be defined as the point where: (a) Working stress ends and breaking stress begins (b) Breaking stress ends and working stress begins (c) Elastic behavior ends and plastic behavior begins (d) Plastic behavior ends and elastic behavior begins
(c) Elastic behavior ends and plastic behavior begins
A pure silicon chip consist of single crystal of silicon. Which one of the following types of corrosion is LEAST LIKELY TO OCCUR? (a) Crevice (b) Stress (c) Intergranular (d) Pitting
(c) Intergranular
Passivity is due to: (a) Higher EMF (b) Lower EMF (c) Oxide film (d) All
(c) Oxide film
Shape of true stress-strain curve for a material depends on (a) Strain (b) Strain rate (c) Temperature (d) All
(d) All
Read the following statements CAREFULLY: 1. Corrosion is an oxidation reaction. 2. Corrosion is a combination of chemical and physical process. 2. Corrosion involves the loss of material. Which one of the above are TRUE ABOUT CORROSION? (a) 1 and 2 (b) 1 and 3 (c) 2 and 3 (d) All of the above
(d) All of the above
Process of corrosion is accelerated by: (a) Air and moisture (b) Electrolytes in water (c) Metallic impurities (d) All of these
(d) All of these
Figure-out the odd point in the following (a) Proportional limit (b) Elastic limit (c) Yield point (d) Fracture point
(d) Fracture point
In the figure, the tensile stress corresponds to stress at point: (a) T (b) U (c) W (d) X
(d) X
ASSERTION: Ceramics are generally more stable than metals in physiological environment. REASON: Water molecules can dissolve ionic compounds. Note: In the following questions a statement of assertion followed by the statement of reason is given. Choose the correct answer out of the following choices. (i) Assertion and reason both are correct statements but reason does not explain assertion. (ii) Assertion and reason both are correct statements and reason explains the assertion. (iii) Both assertion and reason are wrong. (iv) Assertion is a correct statement and reason is a wrong statement. (v) Assertion is a wrong statement and reason is correct statement.
(i) Assertion and reason both are correct statements but reason does not explain assertion.
Springs deforms permanently after prolonged use, because of: (a) Rigidity (b) Elastic fatigue (c) Plastic fatigue (d) Hooke's Law
(b) Elastic fatigue
In this figure, Elastic zone is: (a) O-T (b) O-U (c) O-W (d) O-X
(b) O-U
Toughness of a material is equal to area under ______________ part of the stress-strain curve. (a) Elastic (b) Plastic (c) Both (d) None
(c) Both
Corrosion is a chemical reaction that involves: (a) The inside of the object changing from an element to a compound. (b) The surface of the object changing from an element to a compound. (c) Nothing happens (d) The surface of the object changing from one element into another element.
(b) The surface of the object changing from an element to a compound.
In the figure, permanent deformation occurs if the stress is increased beyond: (a) T (b) U (c) W (d) X
(b) U
Passivity is not reason for inertness of the following: (a) Au (b) Al (c) Ti (d) Ni
(a) Au
Materials that show very small plastic range beyond elastic limit is called: (a) Brittle materials (b) Elastomers (c) Elastic (d) Ductile materials
(a) Brittle materials
In this figure, which of the following is NOT true in the region OT: (a) Extension is not proportional to the applied force (b) Material is not elastic (c) Material is elastic (d) The slope gives the Young's modulus
(a) Extension is not proportional to the applied force (b) Material is not elastic
The final point on the stress-strain graph is called: (a) Fracture point (b) Yield point (c) Elastic point (d) Proportional limit
(a) Fracture point
Lower the pH, corrosion is: (a) Greater (b) Lower (c) Constant (d) None of the above
(a) Greater
High elastic modulus in materials arises from (a) High strength of bonds (b) Weak bonds (c) Combination of bonds (d) None
(a) High strength of bonds
The constant of proportionality in Hooke's law is: (a) Modulus of elasticity (b) Strain (c) Restoring force (d) Stress
(a) Modulus of elasticity
Which of the following is the most stable state of metal? (a) Ore of metal (b) Pure metal (c) Corroded metal (d) Metal ion
(a) Ore of metal
Corrosion do to the form of cavities around the metal is called as the ______________________ (a) Pitting corrosion (b) Stress corrosion (c) Intergranular corrosion (d) Galvanic corrosion
(a) Pitting corrosion
In a tensile test, at the end of elastic zone, the: (a) Tensile strain increases more quickly (b) Tensile strain decreases more quickly (c) Tensile strain increases in proportion to the stress (d) Tensile strain decreases in proportion to the stress (e) Tensile strain remains constant
(a) Tensile strain increases more quickly
In this figure, T is: (a) The limit of proportionality (b) Yield Strength (c) Ultimate Strength (d) Fracture Point
(a) The limit of proportionality
Steel has a greater modulus of elasticity than rubber because under the same stress: (a) The strain in steel is less than rubber (b) The strain in steel is more than rubber (c) Elongation in steel is more than rubber (d) None of the above
(a) The strain in steel is less than rubber
State true or false. Due to corrosion, useful properties of metals such as malleability, ductility, and electrical conductivity are lost. (a) True (b) False
(a) True
Plastic deformation results from the following: (a) Slip (b) Twinning (c) Both (d) None
(c) Both
ASSERTION: Hydrophilic polymers have low molecular weight with less cross-link points. REASON: Chain entanglements restricts the influx of water molecules. Note: In the following questions a statement of assertion followed by the statement of reason is given. Choose the correct answer out of the following choices. (i) Assertion and reason both are correct statements but reason does not explain assertion. (ii) Assertion and reason both are correct statements and reason explains the assertion. (iii) Both assertion and reason are wrong. (iv) Assertion is a correct statement and reason is a wrong statement. (v) Assertion is a wrong statement and reason is correct statement.
(i) Assertion and reason both are correct statements but reason does not explain assertion.
ASSERTION: Hydrophilic polymers will swell in the physiological environment. REASON: Water molecules in polymer chains reduces glass transition temperature. Note: In the following questions a statement of assertion followed by the statement of reason is given. Choose the correct answer out of the following choices. (i) Assertion and reason both are correct statements but reason does not explain assertion. (ii) Assertion and reason both are correct statements and reason explains the assertion. (iii) Both assertion and reason are wrong. (iv) Assertion is a correct statement and reason is a wrong statement. (v) Assertion is a wrong statement and reason is correct statement.
(i) Assertion and reason both are correct statements but reason does not explain assertion.
ASSERTION: A biopolymer with Tg = 50 degrees Celsius , will be difficult to hydrolyze under physiological conditions. REASON: Rubbery state of a polymer encourages water penetration. Note: In the following questions a statement of assertion followed by the statement of reason is given. Choose the correct answer out of the following choices. (i) Assertion and reason both are correct statements but reason does not explain assertion. (ii) Assertion and reason both are correct statements and reason explains the assertion. (iii) Both assertion and reason are wrong. (iv) Assertion is a correct statement and reason is a wrong statement. (v) Assertion is a wrong statement and reason is correct statement.
(ii) Assertion and reason both are correct statements and reason explains the assertion.
ASSERTION: Crosslinked polymers degrades faster. REASON: Crosslinked polymers will have fewer primary and secondary interactions holding the material together, hence degrades faster. Note: In the following questions a statement of assertion followed by the statement of reason is given. Choose the correct answer out of the following choices. (i) Assertion and reason both are correct statements but reason does not explain assertion. (ii) Assertion and reason both are correct statements and reason explains the assertion. (iii) Both assertion and reason are wrong. (iv) Assertion is a correct statement and reason is a wrong statement. (v) Assertion is a wrong statement and reason is correct statement.
(iii) Both assertion and reason are wrong.
ASSERTION: Stress induced degradation can occur in ceramics under tension. REASON: It is easier for ceramic materials to deform plastically, resulting in their brittleness. Note: In the following questions a statement of assertion followed by the statement of reason is given. Choose the correct answer out of the following choices. (i) Assertion and reason both are correct statements but reason does not explain assertion. (ii) Assertion and reason both are correct statements and reason explains the assertion. (iii) Both assertion and reason are wrong. (iv) Assertion is a correct statement and reason is a wrong statement. (v) Assertion is a wrong statement and reason is correct statement.
(iv) Assertion is a correct statement and reason is a wrong statement.
A perfectly rigid body is one: (a) Which does not move on application of force (b) Whose shape and size change application of force (c) Whose shape and size do not change on application of force (d) Which flows on application of force
BEST ANSWER (a) Which does not move on application of force ALSO CORRECT (c) Whose shape and size do not change on application of force
What do chain entanglements restrict?
The influx of water molecules
Given below are data from in-vitro degradation on PLGA and PCL. Solid samples of each polymer were prepared and incubated for defined time periods in phosphate buffer saline pH 7.4. After incubation, each sample was washed with pure water, dried under vacuum, and then the average molecular weight of polymer chains in the sample was measured using gel permeation chromatography. Based on the date and experimental details, are these polymers exhibiting bulk or surface degradation? time (hr) PLGA MW (g/mole) PCL MW (g/mole) 0 24600 61800 500 9600 58700 1000 3400 56100 1500 1600 53500 2000 900 51000
The key clue lies the details of the experiment as described above—the entire samples are dried, dissolved, and the molecular weights of chains in the samples measured. Recall that the bulk polymer in surface-eroding polymers remains unaffected during degradation; only the surfaceattacked polymer is degraded. Here, we are essentially told that all of the polymer is experiencing a reduction in molecular weight; this is the characteristic feature of bulk erosion.
Nanoparticle induced improvement in mechanical properties of polymers matrix is primarily due to: a. Uniform dispersion b. Chemical structure c. Large aspect ratio d. All of the above
a. Uniform dispersion
Diamond, carbon nanotubes and graphite are: a. Isotropes of C b. Allotropes of C c. Similar crystal structure d. All of the above
b. Allotropes of C
Which of the following is NOT true about graphene: a. Hydrophobicity b. Strongest, lightest, most conductive 1 dimensional nanomaterial c. One-atom thick of carbon atoms arranged in a hexagonal lattice d. All of the above
b. Strongest, lightest, most conductive 1 dimensional nanomaterial *** graphene is 2 dimensional
Magnetic nanoparticles are suitable for magnetic hyperthermia, primarily due to: a. Small size b. Strong inter-particle interactions c. Ions with different valency d. All of the above
c. Ions with different valency
Carbon nanotubes and graphite: a. Possess anisotropy b. Biocompatible at all concentration c. Posses high chemical reactivity d. All of the above
c. Posses high chemical reactivity
Which of the following is NOT true about the carbon nanotubes (CNTs): a. Strong C-C covalent bond b. Strong Van der Walls bond between tubes c. Weak Van der Walls bond between tubes d. sp^2 hybridized C atom
c. Weak Van der Walls bond between tubes
Which of the following may not be a good idea to prevent agglomeration of magnetic nanoparticles: a. Coating with a polymer b. Coating with a silicate layer c. Attaching a surfactant d. Wrapping up with CNTs
d. Wrapping up with CNTs
hyrdophilic polymers have a low molecular weight with _____________.
less cross-linked points
Under what conditions will it be difficult to hydrolyze a biopolymer with Tg= 50 degrees Celsius?
physiological
Where will hyrdrophilic polymers swell?
physiological environments
What reduces the glass transition temperature in polymer chains?
water molecules
What does the rubbery state of a polymer encourage?
water penetration
