This set of Multiple Choice Questions & Answers (MCQs) focuses on “Nanomaterials – Set 3”.
1. In template based synthesis, an electrical insulator is required for the_______
a) Chemical vapour deposition
b) Physical vapour deposition
c) Electrochemical deposition
d) Lithography
View Answer
Explanation: Chemical and physical vapour deposition does not require electrically inert templates and lithography is not a template based synthesis technique. Electrochemical deposition requires an electric insulator with template to prevent the template.
2. In template directed synthesis, template materials should be _______
a) Chemically inert and thermally reactive
b) Chemically inert and thermally inert
c) Chemically reactive and thermally reactive
d) Chemically reactive and thermally active
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Explanation: In template based synthesis, templates should not be harmed or damaged so it must be chemically inert for prevention from chemicals and thermally inert for prevention from temperature damages.
3. What is the correct order of steps in electrochemical deposition?
a) Oriented diffusion of uncharged growth species and then reduction at electrode
b) Oriented diffusion of charged growth species and then reduction at electrode
c) Random diffusion of uncharged growth species and then reduction at electrode
d) Random diffusion of charged growth species and then reduction at electrode
View Answer
Explanation: Electrochemical deposition is the deposition of charged species at electrode which is achieved by diffusion of species under an electric potential (oriented diffusion) and reduction of these species at electrode.
4. Electrochemical deposition is not applicable to ________
a) Metals
b) Semiconductors
c) Alloys
d) Polymers
View Answer
Explanation: In electrochemical deposition, when species are deposited on electrode then current has to pass through deposited material first to complete the circuit. If deposited material is insulating then process will stop.
5. Electrophoretic method does not requires growth species to be________
a) Electrically conductive
b) Electrically insulating
c) Chemically reactive
d) Physically reactive
View Answer
Explanation: In electrophoretic method growth species have charge on their surface but they are not charged species and when they deposits they lose their charge to electrode. Species should not be chemically and physically inert as they requires to coagulate and form bonds with each other.
6. Which one is not correct about the template filling method for synthesis for nanowires and tubes?
a) Template materials should be chemically inert
b) Wettability of pore wall should be good enough
c) Weak adhesion strength leads to nanowires
d) Strong adhesion strength leads to nanowires
View Answer
Explanation: Template material should be chemically inert so that no permanent bonds forms. Wettability should be good so that material fills properly in pores and weak adhesion strength leads to solidification from centre which leads to nanowires and strong adhesion leads to solidification from pore wall so tubes are formed.
7. Which is the best method to make metal nanowires by template filling methods?
a) Colloidal solution filling
b) Melt solution filling
c) Chemical vapour deposition
d) Deposition by centrifugation
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Explanation: Other methods uses precursors which have some elements which can be incorporated during synthesis as impurities while in melt solution filling, melted form of metals are used so chance of impurities is very small.
8. Which one is not a template based synthesis?
a) Electrochemical deposition
b) Electrophoretic deposition
c) Electrospinning
d) Colloidal solution filling
View Answer
Explanation: Electrospinning is not a template based method, it uses electrical forces to control the structure of nanowires and in other methods templates are used to control the structure of nanowires.
9. Ejection of jet of charged species, in electrospinning method, occurs when_______
a) Electric forces overcomes surface tension
b) Surface tension overcomes electric forces
c) Centripetal forces overcome electric forces
d) Electric forces overcome centripetal forces
View Answer
Explanation: No centripetal force is involved in electrospinning method to form nanowires. Electric forces at surface should overcome the surface tension so that a jet of charged species is observed which on solidification will give nanowire.
10. Which one is not a bottom-up approach to synthesise nanowires?
a) Lithography
b) Electrospinning
c) Electrophoretic deposition
d) Template filling
View Answer
Explanation: Lithography is top-down approach while others are bottom-up approaches to synthesise nanowires or nanotubes. Electrospinning uses charge jet to form nanowires. Template filling utilizes pores of templates to synthesis nanowires. Electrophoretic deposition uses template filling under electric field.
Sanfoundry Global Education & Learning Series – Nanomaterials.
To practice all areas of Nanomaterials, here is complete set of Multiple Choice Questions and Answers.
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