This set of Ceramics Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Fullerenes and Nanotubes”.
1. How many pentagonal and hexagonal faces does C60 have?
a) 12, 20
b) 12, 25
c) 20, 12
d) 25, 12
View Answer
Explanation: C60 has 12 pentagonal and 20 hexagonal faces. This allows proper formation of curved sheets of carbon atoms giving it soccer ball type structure.
2. How many pentagonal and hexagonal faces does C70 have?
a) 12, 20
b) 12, 25
c) 20, 12
d) 25, 12
View Answer
Explanation: C70 has 12 pentagonal and 25 hexagonal faces. This is due to more number of carbon atoms and to form perfectly soccer ball shape.
3. Which type of bond is present between C60 molecules?
a) Hydrogen bonding
b) Covalent bonding
c) Dipole-dipole interactions
d) Van der Waals forces
View Answer
Explanation: In solid state, the C60 molecules bind with each other through weak van der Waals forces and can have FCC arrangement. Covalent bonding is present between carbon atoms of this molecule. Van der Waals forces allow some slip and movement of layers.
4. Which of the following elements is most suitable to be added into C60 to form compounds?
a) Alkaline earth metals
b) Alkali metals
c) Transition metals
d) Metalloids
View Answer
Explanation: The structure of fullerenes consists of octahedral and tetrahedral interstices. Alkali metals have size that can fit in the interstices. So we get compounds like K3C60 and Rb3C60. These doped fullerenes act as superconductors.
5. What is the general formula of fullerene structures?
a) C60
b) C2a
c) Ca
d) C2a-1
View Answer
Explanation: The general formula of fullerene is Ca where ‘a’ takes small or large values. In each case, the structure has 12 uniformly distributed pentagons connecting other hexagons.
6. What is the crystal structure of C60?
a) BCC
b) SCC
c) BCT
d) FCC
View Answer
Explanation: C60 has FCC crystal structure. At low temperatures the structure may become simple cubic. The FCC structure has lot of interstices.
7. How is a carbon nanotube produced?
a) CVD process
b) Physical vapor deposition process
c) Continuous refining
d) Solution process
View Answer
Explanation: Carbon from a host material like polymers or methane gas is passed through an inert channel containing substrate. Due to high temperature, carbon atoms are precipitated on the substrate and the layer is rolled up carefully to form a nanotube.
8. Carbon nanotubes are much stronger than steel.
a) True
b) False
View Answer
Explanation: Carbon nanotubes have carbon to carbon covalent bond inter-locking system which does not allow lot of movements. It doesn’t have grains or grain boundaries that will cause weak spots in the material. This contributes to the strength of carbon nanotubes.
9. Carbon nanotubes conduct heat and electricity just like __________
a) Silicon
b) Germanium
c) Copper
d) Steel
View Answer
Explanation: Carbon nanotubes conduct heat and electricity by vibration of covalent bonds that hold the carbon atoms together. This conductivity value is nearly equal to that of copper.
10. Carbon nanotubes have not found a lot of commercial applications.
a) True
b) False
View Answer
Explanation: Carbon nanotubes have actually found a lot of commercial applications because of the properties induced due to their size. These include engineering plastics, polymers, displays, anti-corrosion paints, thin films and many more ongoing research works.
Sanfoundry Global Education & Learning Series – Ceramics Engineering.
To practice all areas of Ceramics Engineering, here is complete set of Multiple Choice Questions and Answers.
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