This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Nanotechnology”.
1. Which of the following is an example of top-down approach for the preparation of nanomaterials?
a) Gas phase agglomeration
b) Molecular self-assembly
c) Mechanical grinding
d) Molecular beam epitaxy
View Answer
Explanation: Mechanical grinding is an example of top-down approach for the preparation of nanomaterials. All the other options are the example of bottom-up approach.
2. Which of the following is an example of bottom-up approach for the preparation of nanomaterials?
a) Etching
b) Dip pen nano-lithography
c) Lithography
d) Erosion
View Answer
Explanation: Dip pen nanolithography is an example of bottom-down approach for the preparation of nanomaterials. All the other options are the example of top-down approach.
3. The properties like melting point, solubility, color, etc changes on varying the ___________
a) Size
b) Composition
c) Surface properties
d) None of the mentioned
View Answer
Explanation: The properties like melting point, solubility, color, etc changes on varying the size of the particles. These all are the physical properties and depends upon the physical characteristics of the particle.
4. The properties like dispersibility, conductivity, etc changes on varying the ___________
a) Size
b) Composition
c) Surface properties
d) None of the mentioned
View Answer
Explanation: The properties like dispersibility, conductivity, etc changes on varying the surface properties of the nanoparticle. These all are the chemical properties and depend upon the surface characteristics of the particle.
5. Quantum confinement results in ___________
a) Energy gap in semiconductor is proportional to the inverse of the square root of the size
b) Energy gap in semiconductor is proportional to the inverse of the size
c) Energy gap in semiconductor is proportional to the square of size
d) Energy gap in semiconductor is proportional to the inverse of the square of size
View Answer
Explanation: The energy gap in a semiconductor is proportional to the inverse of the square of the size. This effect is a result of quantum confinement.
6. Which of the following is the principal factor which causes the properties of nanomaterials to differ significantly from other materials?
a) Size distribution
b) Specific surface feature
c) Quantum size effects
d) All of the mentioned
View Answer
Explanation: Size distribution, specific surface feature and quantum size effects are the principal factor which causes the properties of nanomaterials to differ significantly from other materials.
7. Select the incorrect statement from the following options.
a) Self-assembly is a top-down manufacturing technique
b) In self-assembly, weak interactions play very important role
c) Self-assembling molecules adopt an organised structure which is thermodynamically more stable than the single, unassembled components
d) Compared to the isolated components, the self-assembled structure has a higher order
View Answer
Explanation: Self-assembly is a bottom-down manufacturing technique. All the other options are correct. In self-assembly, weak interactions play very important role, self-assembling molecules adopt an organised structure which is thermodynamically more stable than the single, unassembled components.
8. Which of the following is the application of nanotechnology to food science and technology?
a) Agriculture
b) Food safety and biosecurity
c) Product development
d) All of the mentioned
View Answer
Explanation: The application of nanotechnology to food science and technology are agriculture, food safety and biosecurity, product development, food processing and ingredient technologies.
9. What are the advantages of nano-composite packages?
a) Lighter and biodegradable
b) Enhanced thermal stability, conductivity and mechanical strength
c) Gas barrier properties
d) All of the mentioned
View Answer
Explanation: The advantages of nano-composite packages are-Lighter and biodegradable, enhanced thermal stability, conductivity, mechanical strength and gas barrier properties.
10. The efficiency of today’s best solar cell is about ___________
a) 15-20%
b) 40%
c) 50%
d) 75%
View Answer
Explanation: The efficiency of today’s best solar cells is about 40%. A solar cell or photovoltaic cell is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect.
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