Engineering Questions with Answers - Multiple Choice Questions
Unit Processes MCQ’s – Aromatic Hydrocarbon Oxidation
1 - Question
Benzene presents a very stable configuration.
a) True
b) False
View Answer
Explanation: Benzene presents a very stable configuration toward both thermal dissociation and oxidation. The primary effect of exposure of benzene to elevated temperatures is the dissociation of a hydrogen atom accompanied by the joining of the residues to form diphenyl, a more stable substance which may be recovered in good yield.
2 - Question
Benzene can also be used to produce Maleic acid?
a) Yes
b) No
View Answer
Explanation: Continued oxidation of benzene leads to rupture of the ring and results in the formation of maleic acid, which may be obtained in good yields.
3 - Question
Ring component exhibits the characteristic stability of the aromatic compounds.
a) True
b) False
View Answer
Explanation: The oxidation of hydrocarbons having an aromatic nucleus and one or more side chains may be effected in the side chain without marked rupture of the ring itself, since each component behaves more or less as it would if it alone constituted the major part of the molecule. Thus, the ring component exhibits the characteristic stability of the aromatic compounds.
4 - Question
Toluene can be oxidized to produce what?
a) Benzaldehyde
b) Benzoic acid
c) O-xylene
d) All of the mentioned
View Answer
Explanation: Toluene may be oxidized to benzaldehyde or benzoic acid; o-xylene, to phthalic anhydride; ethylbenzene, to benzoic acid; etc.
5 - Question
Under which temperature, with a mild catalyst does toluene oxidize to benzaldehyde?
a) High
b) Moderate
c) Low
d) None of the mentioned
View Answer
Explanation: High temperatures, mild catalysts, and short times of contact promote the formation of benzaldehyde.
6 - Question
The oxidation of toluene depends on which condition?
a) Catalyst
b) Temperature
c) Oxygen ratio
d) All of the mentioned
View Answer
Explanation: The products of toluene oxidation, chiefly benzaldehyde, benzoic acid, maleic acid, and anthraquinone, are obtained in proportions that depend upon catalyst, temperature, oxygen ratio, and time of contact.
7 - Question
What is produced by dehydrogenating ethylbenzene over a zinc oxide catalyst?
a) Benzaldehyde
b) Styrene
c) Nylon-6
d) Benzoic acid
View Answer
Explanation: Styrene is prepared by dehydrogenating ethylbenzene over a zinc oxide catalyst at approximately 600°C.
8 - Question
What type of reaction is a dehydrogenation reaction?
a) Exothermic
b) Endothermic
c) Neutral
d) None of the mentioned
View Answer
Explanation: The dehydrogenation reaction is endothermic, and a considerable amount of heat has to be added to the converter in order to maintain the reaction temperature.
9 - Question
Which oxidizing agent is used for the conversion of xylene isomers to phthalic acid?
a) Zinc oxide
b) Iron
c) Nitric oxide
d) Vanadium
View Answer
Explanation: Only two oxidation agents have been used in the past for conversion of xylene isomers to phthalic acids-air and nitric acid. No single process has been found completely satisfactory for use with all three isomers, and at present a different process is used for each.
10 - Question
Naphthalene is not very stable.
a) True
b) False
View Answer
Explanation: It is highly stable. The stability of the naphthalene structure is such that, at temperatures up to 400-500°C, a catalyst is necessary for commercial rates of oxidation with air as the oxidizing agent.