This set of Nanotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Production of Fullerene”.
1. Why isn’t the technique of low pressure hydrocarbon flames being commercially used for the production of fullerene?
a) Expensive method
b) Exothermic process
c) Low scale production
d) Low pressure process
View Answer
Explanation: Since the discovery of fullerenes, several methods for fullerene production have been invented. However, only arc discharge method could be used for its commercial production on a large scale. This is because other methods such as low pressure hydrocarbon flames or laser vaporization of carbon have lower yield and expensive production rates respectively. Therefore, these methods cannot reach the fullerene output level available with a sealed-up arc discharge process.
2. Choose the correct order for the arc discharge method.
a) Liquid chromatography ➔ Sooty materials recovered ➔ Inert atmosphere applied ➔ Evaporation of carbon electrodes ➔ Solvent extraction
b) Solvent extraction ➔ Sooty materials recovered ➔ Inert atmosphere applied ➔ Liquid chromatography ➔ Evaporation of carbon electrodes
c) Inert atmosphere applied ➔ Evaporation of carbon electrodes ➔ Sooty materials recovered ➔ Solvent extraction ➔ Liquid chromatography
d) Evaporation of carbon electrodes ➔ Solvent extraction ➔ Liquid chromatography ➔ Inert atmosphere applied ➔ Sooty materials recovered
View Answer
Explanation: Arc discharge method is the most widely used process for fullerene production. In this process carbon electrodes are evaporated in the presence of an inert atmosphere. A sooty material is recovered which contains mainly C60 and C70 with traces of higher order fullerenes such as C76, C78, C84 etc. The fullerenes in the soot are then extracted by solvent extraction method in toluene or benzene. Further, liquid chromatography is carried out to separate the different members of fullerene family.
3. Pentagon road is followed in which of the following conditions?
a) Ultra high yield conditions
b) High yield conditions
c) Ultra low yield conditions
d) Low yield conditions
View Answer
Explanation: The Pentagon road is the path that is followed in the high yield conditions. It requires the temperature for cluster growth to be high enough to anneal the open structures as they grow. But this temperature shouldn’t be extremely high so as to convert the open pentagon road structure to the closed fullerene.
4. Which among the following components is not present in an arc discharge system?
a) RHEED Gun
b) Quartz tube
c) Furnace
d) Carbon electrodes
View Answer
Explanation: The arc discharge method for fullerene production has various components in the system. The parts of the apparatus include furnace for heating purpose, carbon electrodes, tube made out of quartz through which buffer gas is passed for annealing process, a trap that is water cooled and a high voltage pulsed power input.
5. Who is the first computer-controlled commercial producer of fullerene?
a) ONGC
b) NABARD
c) OIL
d) MER Corporation
View Answer
Explanation: MER Corporations were the first to offer fullerenes commercially. Soon after the invention of arc discharge method for fullerene production in 1990, MER Corporations developed arc reactors that operated manually. It was only in 1992 that automated computer controlled reactors were developed by the Corporation. These could operate without any attendance for several days.
6. Which among the following gases should not be used for fullerene production in laser vaporization of carbon?
a) Helium
b) Water vapour
c) Carbon-monoxide
d) Neon
View Answer
Explanation: Laser vaporization of carbon is the oldest method for production of fullerene. It requires an inert atmosphere that favours the growth of fullerene. Other possibilities for the atmosphere include carbon monoxide, carbon dioxide and nitrogen. Hydrogen containing gases such as H2O should not be used as they prevent the growth of fullerene.
7. How can different members of fullerene family be separated after their production?
a) Sedimentation
b) Liquid chromatography
c) Vacuum distillation
d) Solvent extraction
View Answer
Explanation: During the production of fullerene, several members of its family are produced. Stable fullerene such as C60 and C70 are produced in majority, followed by higher order fullerene like C76, C78, C84 etc. that are obtained in lesser amounts. The members of fullerene family can be separated from each other using the liquid chromatography.
8. Which of the following is used as a solvent in the Kratschmer-Huffman method of fullerene production?
a) Toluene
b) Water
c) Sulphur dioxide
d) Methanol
View Answer
Explanation: Solvent extraction of fullerene in arc discharge method is done using toluene. Fullerene solids are extracted from carbon soots that are collected from the installed arc discharge system. After extraction the solvent is removed from fullerene by concentrating them in rotary evaporator.
9. Field induced high intensity plasma for fullerene production has high potential to serve as an alternative to arc discharge process. Why is it so?
a) Inexpensive powder
b) Conductive hydrocarbon gas
c) Poor yield
d) Batch process
View Answer
Explanation: Since the discovery of fullerene, arc discharge method is the only commercially applied process for fullerene production. No other method has been able to reach the fullerene output level available with arc discharge. However, the field-induced high intensity plasmas have great potential to produce fullerene on a large scale. This method can use inexpensive powder, non-conductive carbon or hydrocarbon gases as starting materials. The method can also be continuous and automated.
10. Who are the inventors of the arc discharge method used for synthesizing graphene?
a) Hoffman and Hoffman
b) Kratschmer and Hoffman
c) Woldridge and Hoffman
d) Huffman and Huntington
View Answer
Explanation: Scientist Kratschmer and Huffman had developed the Arc Discharge method for production of fullerenes in 1990s. Macroscopic quantities of fullerene were first produced using this method. Till date this method remains the major tool for synthesizing fullerenes.
11. Which of the following is not a method of production of fullerene?
a) Carbon arc
b) Hydrocarbon flame
c) Field-induced hot carbon plasma
d) Mechanical exfoliation
View Answer
Explanation: Over the time, researchers have discovered various methods for the synthesis of fullerene. These include carbon arc, hydrocarbon flame, field-induced hot carbon plasma and laser vaporization of carbon methods. However, arc discharge method is the only full-fledged commercial process of fullerene production. Mechanical exfoliation, on the other hand, is used for graphene production.
12. Which among the following was the first method of production of fullerene?
a) Laser vaporization of oxygen in an inert atmosphere
b) Laser vaporization of nitrogen in an inert atmosphere
c) Laser vaporization of hydrogen in an inert atmosphere
d) Laser vaporization of carbon in an inert atmosphere
View Answer
Explanation: Vaporization of carbon with a laser beam in an inert atmosphere was the first method used for the production of fullerene. Here, other than inert gases, carbon monoxide, carbon dioxide and nitrogen could be used as possible atmosphere. Hydrogen containing gases such as water vapour were not used as they hindered the growth of fullerene. This method generated microscopic amounts of fullerene.
Sanfoundry Global Education & Learning Series – Nanotechnology.
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