This set of Nanotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Nanoporous Materials”.
1. Which of these applications of nanoporous aerogels is not because of its high porosity?
a) Gas filters
b) Catalysts
c) Blankets
d) Sensors
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Explanation: The high porosity of silica aerogels can be used for applications such as gas filters, absorbing media for desiccation and waste contaminant, encapsulation media and hydrogen fuel storage. Due to the high porosity of aerogels they have high potential as catalysts, sensor and ICs.
2. Why are aerogels used as thermal insulators?
a) Low density
b) High surface activities
c) Low thermal conductivity
d) High permeability
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Explanation: Aerogels have very low thermal conductivity ⁓ 1% – 10% of a solid. In addition, they possess very small particles linked in a three-dimensional network with many dead ends. This hinders the transport of thermal energy through the solid portion of an aerogel leading to thermal insulation.
3. What property enables aerogels to act as chemical absorbers for cleaning up spills?
a) High surface area
b) Low density
c) Hydrophobicity
d) High thermal resistivity
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Explanation: The high surface area of aerogels per unit mass helps them to act as chemical absorbers for cleaning up spills. In addition to that, they have a great potential as catalysts or catalyst carriers.
4. These biodegradable nanoporous materials obtained from a polysaccharide have a wide application in biomaterial construction. What are these?
a) Pyrrole nanostructures
b) Nanoporous chitosan
c) Nanoporous copper
d) Nanoporous silica aerogel
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Explanation: Nanoporous chitosan materials obtained from chitosan, a linear polysaccharide, could be used for a wide variety of applications in biomaterial construction and many other areas of science. It can have its applications in chemical separation, drug delivery and wastewater remediation.
5. Identify a property that does not make nanoporous aerogels suitable for sensors.
a) High overall porosity
b) High corrosivity
c) High surface activities
d) High pore accessibility
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Explanation: Aerogels possess high overall porosity, high pore accessibility and high surface activities which make them potential candidates as sensors. With the increase in humidity the electric resistance decreases for silica nanoporous aerogel thin films. This is attributed to the pore structure of the material.
6. Electrospun nanofibrous aerogels hold great potential for separating oily wastewater during oil spill accidents.
a) True
b) False
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Explanation: Electrospun nanofibers possess several properties such as tunable wettability, large surface area, good pore accessibility, decent flexibility, high porosity, oil sorption capacity, ease in scalability and production from various materials such as polymers, ceramic, carbon etc. These features hold great potential for separating oily waste water. These nanofibers can not only drive the oil into its voids between fibers but also into its multipores.
7. Why are nanoporous carbon materials useful for the development of supercapacitors?
a) Good buoyancy
b) High priced
c) Enhanced sorption rate
d) Superior stability
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Explanation: Nanoporous carbon materials have come out as potential electrode materials for supercapacitors primarily due to several desirable properties such as wide allotrope forms, high surface area, large pore volume, superior stabilities and low costs.
8. Choose the incorrect statement from the following.
a) Silica aerogel films have been employed in dye-sensitized solar cells
b) Aerogels cannot be used in drug delivery due to their incompatibility with body
c) Aerogels are commercially used in blankets, sleeping bags and insoles
d) Silica aerogels are used as insulators in semitransparent roof
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Explanation: Aerogels can be used in drug delivery systems due to their biocompatibility. Silica aerogel was used as an insulator in the semitransparent roof as the first residential use in the Georgia Institute of Technology’s Solar Decathlon House. They are also used for dye – sensitized solar cells. Sleeping bags and aerogel insoles are commercially sold for mountain climbers.
9. How are aerogels useful in space research and exploration?
a) Absorbs organic solvents
b) Conducts thermal energy
c) Diffuses charge
d) Traps dust particles
View Answer
Explanation: Aerogels have also found their way into space research and exploration. NASA has made use of nanoporous aerogels inorder to trap space dust particles aboard the stardust spacecraft. These particles tend to vaporise on impact with solids and pass through gases. However, aerogels have the capability of trapping them. Aerogels were also used for thermal insulation of Mars Rover and Space suits.
More MCQs on Nanoporous Materials:
Sanfoundry Global Education & Learning Series – Nanotechnology.
To practice all areas of Nanotechnology, here is complete set of 1000+ Multiple Choice Questions and Answers.
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