1.Naphthalene is the largest single component of which coal-tar fraction?
a) Light oil
b) Middle oil
c) Heavy oil
d) Anthracene oil
Answer: b) Middle oil
Explanation: Naphthalene is obtained mainly by cooling the middle oil fraction (160–230°C) during coal-tar distillation, where it crystallizes out.
2.Which position does naphthalene most readily undergo electrophilic substitution?
a) 1-position
b) 2-position
c) 4-position
d) 8-position
Answer: a) 1-position
Explanation: The 1-position is favored because the resulting carbocation intermediate is stabilized by resonance, making substitution at this site predominate.
3.The resonance energy of naphthalene is approximately:
a) 36 kcal/mol
b) 61 kcal/mol
c) 84 kcal/mol
d) 54 kcal/mol
Answer: b) 61 kcal/mol
Explanation: The resonance energy of naphthalene is less than twice that of benzene, indicating it is less aromatic and more reactive.
4.Which is NOT a use of naphthalene?
a) Dyestuffs
b) Insecticides
c) Beta blockers
d) Vasodilators
Answer: d) Vasodilators
Explanation: Vasodilators are not produced from naphthalene; other uses like dyestuffs and insecticides are supported in the document.
5.How is naphthalene primarily isolated from coal tar?
a) Crystallizing from the light oil fraction
b) Sublimation of heavy oil fraction
c) Cooling and crystallization of the middle oil fraction
d) Steam distillation of residual oil
Answer: c) Cooling and crystallization of the middle oil fraction
Explanation: Naphthalene crystallizes out when the middle oil fraction (160–230°C) of coal tar is cooled.
6.Which of the following steps is NOT part of the Haworth synthesis of naphthalene?
a) Formation of 3-benzoyl propanoic acid from benzene and succinic anhydride
b) Reduction of 3-benzoyl propanoic acid to 4-phenyl butanoic acid
c) Formation of tetralone by ring closure
d) Direct halogenation of benzene to form naphthalene
Answer: d) Direct halogenation of benzene to form naphthalene
Explanation: Direct halogenation is not a step in Haworth synthesis.
7.Which reagent is used in step II of the Haworth synthesis for reducing 3-benzoyl propanoic acid?
a) Zinc amalgam and HCl
b) Palladium catalyst under hydrogen
c) Sodium borohydride
d) Aluminum chloride
Answer: a) Zinc amalgam and HCl
Explanation: Amalgamated zinc and HCl reduce the keto group in this step.
8.At what temperature does naphthalene sulfonation produce mostly the 1-sulfonic acid?
a) 50 °C
b) 80 °C
c) 120 °C
d) 150 °C
Answer: b) 80 °C
Explanation: Low-temperature sulfonation (~80 °C) favors the 1-sulfonic acid derivative.
9.Which product predominates when naphthalene undergoes Friedel-Crafts alkylation with iodomethane at low temperature?
a) 2-Methyl naphthalene
b) 1-Methyl naphthalene
c) 1,2-Dimethyl naphthalene
d) 2,3-Dimethyl naphthalene
Answer: b) 1-Methyl naphthalene
Explanation: The 1-methyl derivative forms predominantly at lower temperatures during alkylation.
10.Naphthalene forms addition compounds (e.g., dibromo derivatives) more readily than benzene because:
a) Naphthalene has more reactive alkenes
b) It is less aromatic than benzene
c) It is more polar
d) It contains oxygen functionality
Answer: b) It is less aromatic than benzene
Explanation: The resonance energy of naphthalene is lower than benzene, making it more reactive to addition.
11.Which of the following is not a typical electrophilic substitution on naphthalene?
a) Nitration
b) Sulphonation
c) Bromination
d) Nucleophilic substitution
Answer: d) Nucleophilic substitution
Explanation: Naphthalene mainly undergoes electrophilic substitution; nucleophilic substitutions are less common.
12.What is the effect of temperature on the position of sulfonation in naphthalene?
a) Higher temperature favors 1-sulfonic acid
b) Higher temperature favors 2-sulfonic acid
c) Temperature has no effect
d) Lower temperature favors 2-sulfonic acid
Answer: b) Higher temperature favors 2-sulfonic acid
Explanation: At higher temperatures (~120 °C), sulfonation shifts to the 2-position.
Naphthalene is used medically in:
a) Preparation of anesthetics
b) Insecticides and veterinary dusting powders
c) Cardiac stimulants
d) Antibiotics
Answer: b) Insecticides and veterinary dusting powders
Explanation: Naphthalene’s insecticidal properties make it useful in veterinary applications.
13.Which catalyst is used to form 1-chloronaphthalene by chlorination of naphthalene?
a) FeCl3
b) AlCl3
c) ZnCl2
d) NiCl2
Answer: a) FeCl3
Explanation: Iron(III) chloride catalyzes this electrophilic substitution reaction.
14.What is the melting point of pure naphthalene?
a) 80 °C
b) 60 °C
c) 40 °C
d) −80 °C
Answer: a) 80 °C
Explanation: Pure naphthalene melts at around 80 °C.
15.What happens when naphthalene is nitrated at low temperature?
a) Mainly 2-nitronaphthalene forms
b) Mainly 1-nitronaphthalene forms
c) Dinitro derivatives form exclusively
d) No reaction occurs
Answer: b) Mainly 1-nitronaphthalene forms
Explanation: Electrophilic substitution favors 1-position nitration at low temperature.
16.Which derivative of naphthalene is used in the manufacture of beta-blocker drugs?
a) α-Naphthol
b) Naphthalene sulfonic acid
c) 1-Chloronaphthalene
d) Naphthalene-2-sulfonic acid
Answer: a) α-Naphthol
Explanation: α-Naphthol derivatives are important intermediates in beta-blocker synthesis.
17.The bond length difference in naphthalene between C1-C2 and C2-C3 is explained by:
a) Steric hindrance
b) Resonance structures with varying double bond character
c) Hydrogen bonding
d) Ionic interactions
Answer: b) Resonance structures with varying double bond character
Explanation: Resonance forms show the C1-C2 bond has more double bond character and is shorter.
18.The boiling point of naphthalene is approximately:
a) 218 °C
b) 180 °C
c) 150 °C
d) 300 °C
Answer: a) 218 °C
Explanation: Naphthalene boils near 218 °C.
19.In naphthalene electrophilic substitution, substitution at C-2 occurs when:
a) Reaction temperature is low
b) Using non-polar solvents at high temperature
c) The electrophile is very weak
d) Using polar solvents at low temperature
Answer: b) Using non-polar solvents at high temperature
Explanation: C-2 substitution is favored at high temperature or with bulkier/non-polar conditions.
20.Which reaction of naphthalene yields phthalic anhydride as a product?
a) Oxidation
b) Reduction
c) Nitration
d) Sulfonation
Answer: a) Oxidation
Explanation: Oxidation of naphthalene forms phthalic acids, which upon dehydration yield phthalic anhydride.
21.The major use of naphthalene sulfonic acids is in:
a) Dye production
b) Plasticizers and rubber processing
c) Food preservatives
d) Polymer cross-linking
Answer: b) Plasticizers and rubber processing
Explanation: Naphthalene sulfonates act as plasticizers and are used in rubber manufacturing.
22.Which is the correct formula of naphthalene?
a) C6H6
b) C10H8
c) C14H10
d) C16H10
Answer: b) C10H8
Explanation: Naphthalene consists of two fused benzene rings with the formula C10H8.
23.Naphthalene’s odor is described as:
a) Odorless
b) Aromatic and penetrating
c) Sweet and floral
d) Musty and earthy
Answer: b) Aromatic and penetrating
Explanation: It has a characteristic strong odor common to aromatic compounds.
24.Which compound is primarily used in the production of carbaryl insecticide?
a) Naphthalene
b) Phenanthrene
c) Triphenylmethane
d) Diphenylmethane
Answer: a) Naphthalene
Explanation: Naphthalene is a precursor in carbaryl insecticide manufacture.
25.Which compound is used as a veterinary insecticide dusting powder?
a) Triphenylmethane
b) Anthracene
c) Naphthalene
d) Phenanthrene
Answer: c) Naphthalene
Explanation: Naphthalene’s insecticidal properties make it useful in veterinary dusting powders.
26.Which compound’s sulfonic acid has industrial applications in detergents?
a) Naphthalene
b) Anthracene
c) Diphenylmethane
d) Triphenylmethane
Answer: a) Naphthalene
Explanation: Naphthalene sulfonic acid derivatives are used in detergents and surfactants.
27.Which compound is known for its use as a surfactant when sulfonated?
a) Naphthalene
b) Phenanthrene
c) Anthracene
d) Diphenylmethane
Answer: a) Naphthalene
Explanation: Naphthalene sulfonates serve as industrial surfactants.
28.The primary chemical reaction mechanism for electrophilic substitution on naphthalene is:
a) Free radical substitution
b) Electrophilic aromatic substitution
c) Nucleophilic aliphatic substitution
d) Radical addition
Answer: b) Electrophilic aromatic substitution
Explanation: Aromatic rings undergo electrophilic substitution preferentially.
29.Which hydroxylated derivative of naphthalene is important in the synthesis of pharmaceuticals?
a) α-Naphthol
b) β-Naphthol
c) 2-Nitronaphthalene
d) Naphthalene sulfonic acid
Answer: a) α-Naphthol
30.Explanation: α-Naphthol is a key intermediate in drug synthesis.
The addition of bromine to naphthalene occurs mainly at:
a) 1,2-positions
b) 2,3-positions
c) 4,5-positions
d) 9,10-positions
Answer: a) 1,2-positions
Explanation: Bromine adds across the 1,2-double bond of naphthalene in an addition reaction.
31.Sulfonation of naphthalene at higher temperatures produces:
a) 2-naphthalenesulfonic acid
b) 1-naphthalenesulfonic acid
c) Naphthols
d) Diphenylmethane sulfonate
Answer: a) 2-naphthalenesulfonic acid
32.Explanation: Higher temperatures favor substitution at the 2-position.
Which compound shows higher resistance to electrophilic substitution, naphthalene or benzene?
a) Naphthalene
b) Benzene
c) Both equally reactive
d) Depends on the substituent
Answer: b) Benzene
33.Explanation: Naphthalene is more reactive due to lower resonance stabilization compared to benzene.
Which intermediate is formed during the Haworth synthesis of naphthalene?
a) Tetralone
b) Anthrone
c) Benzophenone
d) Naphthol
Answer: a) Tetralone
Explanation: Tetralone is formed during ring closure in Haworth synthesis.
34.Phenanthrene is a component of the backbone of which natural product?
a) Propranolol
b) Morphine
c) Crystal violet
d) Emodin
Answer: b) Morphine
Explanation: Phenanthrene is identified as the backbone structure in morphine and other alkaloids like codeine.
35.Which reaction synthesizes phenanthrene starting from 4-naphthalen-1-yl-4-oxobutanoic acid?
a) Haworth synthesis
b) Friedel-Crafts alkylation
c) Sandmeyer reaction
d) Aldol condensation
Answer: a) Haworth synthesis
Explanation: The Haworth method is used for the synthesis of phenanthrene as described.
36.Which positions in phenanthrene are most reactive towards electrophilic attack?
a) 1,2
b) 9,10
c) 4,5
d) 2,3
Answer: b) 9,10
Explanation: The 9- and 10-positions are especially reactive due to stabilization of intermediates that preserve aromatic sextets in two rings.
37.Phenanthrene is composed of how many fused benzene rings?
a) Two
b) Three
c) Four
d) One
Answer: b) Three
Explanation: Phenanthrene is a polycyclic aromatic hydrocarbon composed of three fused benzene rings.
38.Phenanthrene fluoresces with which color under UV light?
a) Red
b) Blue
c) Green
d) Yellow
Answer: b) Blue
Explanation: Phenanthrene appears as a white powder exhibiting blue fluorescence.
39.The resonance energy of phenanthrene is approximately:
a) 61 kcal/mol
b) 84 kcal/mol
c) 91 kcal/mol
d) 36 kcal/mol
Answer: c) 91 kcal/mol
Explanation: Phenanthrene has a high resonance energy that contributes to its stability and aromatic character.
40.The Haworth synthesis of phenanthrene involves the use of:
a) Benzene and phthalic anhydride
b) Benzene and succinic anhydride
c) Toluene and chlorine
d) Propane and bromine
Answer: a) Benzene and phthalic anhydride
Explanation: Benzene reacts with phthalic anhydride in the presence of AlCl3 in the Haworth synthesis to form phenanthrene.
41.Phenanthrene, upon oxidation with chromic acid, yields:
a) Phenanthrenequinone
b) Diphenic acid
c) 9,10-Dibromophenanthrene
d) Phenol
Answer: b) Diphenic acid
Explanation: Oxidation of phenanthrene produces phenanthraquinone, which can be further oxidized to diphenic acid.
42.Which compound is formed by bromination of phenanthrene at the 9,10-positions?
a) 9,10-Dibromophenanthrene
b) 1-Bromophenanthrene
c) 4-Bromophenanthrene
d) 2,3-Dibromophenanthrene
Answer: a) 9,10-Dibromophenanthrene
Explanation: Bromination preferentially occurs at the 9,10-positions forming 9,10-dibromophenanthrene.
43.Which steroid-related compounds contain the phenanthrene nucleus?
a) Cholesterol and bile acids
b) Aspirin and paracetamol
c) Antibiotics
d) Anesthetics
Answer: a) Cholesterol and bile acids
Explanation: Steroids such as cholesterol and bile acids contain phenanthrene as part of their core structure.
44.Which of the following is a phenanthrene derivative with antifungal activity?
a) Dithranol
b) Anthraquinone
c) Naphthol
d) Crystal Violet
Answer: a) Dithranol
Explanation: Dithranol is a phenanthrene derivative used clinically for antifungal therapy.
45.What effect does phenanthrene have on skin?
a) Photosensitizing
b) Moisturizing
c) Antiseptic
d) None
Answer: a) Photosensitizing
Explanation: Phenanthrene is known to sensitize skin to sunlight and can cause irritation.
46.Phenanthrene is found in which common environmental pollutant?
a) Cigarette smoke
b) Diesel exhaust only
c) Plastic residues
d) Water pollution only
Answer: a) Cigarette smoke
Explanation: Phenanthrene is one of the PAHs found in cigarette smoke, contributing to toxicity.
47.Which reagent is involved in the Haworth synthesis for the formation of 3,4-dihydrophenanthren-1(2H)-one?
a) Zinc amalgam and HCl
b) Conc. sulfuric acid
c) Sodium borohydride
d) AlCl3
Answer: b) Conc. sulfuric acid
Explanation: Ring closure to form tetralone derivative uses concentrated sulfuric acid.
48.Phenanthrene derivatives, such as papaverine and codeine, possess which pharmacological activity?
a) Analgesic and antispasmodic
b) Antibiotic
c) Anti-inflammatory only
d) Antiviral
Answer: a) Analgesic and antispasmodic
Explanation: These alkaloids have clinically important analgesic and antispasmodic properties.
49.Phenanthrene oxidation in the presence of chromic acid leads to which diketone intermediate?
a) Phenanthraquinone
b) Anthraquinone
c) Naphthaquinone
d) Phthalic anhydride
Answer: a) Phenanthraquinone
Explanation: Chromic acid oxidizes phenanthrene into phenanthraquinone before further oxidation.
50.Which of the following solvents favors acetylation of phenanthrene at the 9-position?
a) Non-polar solvents such as CS2
b) Polar solvents such as nitrobenzene
c) Water
d) Alcohols
Answer: a) Non-polar solvents such as CS2
Explanation: Non-polar solvents promote acetylation at the 9-position preferentially.
51.9,10-Phenanthraquinone is the precursor of:
a) Diphenic acid
b) Alpha-Naphthol
c) Beta-Naphthol
d) Naphthalene sulfonic acids
Answer: a) Diphenic acid
Explanation: Further oxidation converts phenanthraquinone into diphenic acid.
52.Which of the following is NOT a property of phenanthrene?
a) White crystalline powder
b) Soluble in water
c) Blue fluorescence under UV light
d) Photosensitizing effect on skin
Answer: b) Soluble in water
Explanation: Phenanthrene is insoluble in water but soluble in organic solvents.
53.Phenanthrene oxidation products are used in the synthesis of which dyes?
a) Alizarin
b) Indigo
c) Methylene blue
d) Crystal violet
Answer: a) Alizarin
Explanation: Anthraquinone derivatives of phenanthrene are precursors for alizarin dyes.
54.Which is the main cause of toxicity associated with phenanthrene exposure?
a) Carcinogenicity
b) None
c) Sedative effects
d) Anti-inflammatory effects
Answer: a) Carcinogenicity
Explanation: Phenanthrene, a PAH, is toxic and has mutagenic, carcinogenic properties.
55.Which of the following methods is used for the sulfonation of phenanthrene?
a) Conc. sulfuric acid at elevated temperature
b) Cold water treatment
c) Ozonolysis
d) Friedel-Crafts acylation
Answer: a) Conc. sulfuric acid at elevated temperature
Explanation: Sulfonation is carried out with concentrated H2SO4 at elevated temperatures.
56.Which compound’s trisubstituted derivatives show anti-asthmatic activity?
a) Naphthalene
b) Phenanthrene
c) Diphenylmethane
d) Anthracene
Answer: b) Phenanthrene
Explanation: Certain phenanthrene derivatives have been investigated for anti-asthmatic effects.
57.Phenanthrene ring system can be considered as fused:
a) Three benzene rings angularly fused
b) Three benzene rings linearly fused
c) Two benzene rings and one naphthalene ring
d) None of the above
Answer: a) Three benzene rings angularly fused
Explanation: Phenanthrene has angularly fused three benzene rings.
58.Anthracene is primarily obtained from:
a) Middle oil
b) Light oil
c) Anthracene oil
d) Residual oil
Answer: c) Anthracene oil
Explanation: Anthracene is found in the anthracene oil fraction during coal-tar distillation, with concentrations up to 3.5%.
59.Anthracene shows strongest fluorescence under:
a) Visible light
b) Infrared light
c) Ultraviolet light
d) X-rays
Answer: c) Ultraviolet light
Explanation: Anthracene exhibits strong blue fluorescence under UV light.
60.Preferred positions for electrophilic substitution in anthracene are:
a) 1,2
b) 9,10
c) 4,5
d) 2,3
Answer: b) 9,10
Explanation: Electrophilic substitution occurs at the central 9,10-positions, retaining two benzene rings and yielding a stable intermediate.
61.Which method is NOT a preparation method for anthracene?
a) Friedel-Crafts reaction
b) Haworth synthesis
c) Elbs reaction
d) Kolbe-Schmitt reaction
Answer: d) Kolbe-Schmitt reaction
Explanation: The Kolbe-Schmitt reaction is not described as useful for anthracene synthesis.
62.Primary industrial application of anthracene derivatives:
a) Textile dyes
b) Fertilizer additives
c) Painkillers
d) Explosives
Answer: a) Textile dyes
Explanation: Anthracene glycosides and other derivatives are used in natural dye preparation.
63.Anthracene consists of how many fused benzene rings?
a) Two
b) Three
c) Four
d) Five
Answer: b) Three
Explanation: Anthracene is a linear polycyclic aromatic hydrocarbon with three fused benzene rings in a straight line.
64.The resonance energy of anthracene is approximately:
a) 28 kcal/mole
b) 84 kcal/mole
c) 120 kcal/mole
d) 36 kcal/mole
Answer: b) 84 kcal/mole
Explanation: Anthracene has a total resonance energy around 84 kcal/mole, averaging about 28 kcal/mole per ring.
65.Which bond in anthracene is shorter due to higher double bond character?
a) C2–C3
b) C1–C2
c) C3–C4
d) C4–C5
Answer: b) C1–C2
Explanation: X-ray diffraction and resonance structures show C1–C2 has more double bond character, making it shorter.
66.Anthracene synthesis by Friedel-Crafts involves the condensation of:
a) Benzyl chloride with AlCl3
b) Benzene with succinic anhydride
c) O-methyl benzophenone pyrolysis
d) 1,3-butadiene with 1,4-naphthoquinone
Answer: a) Benzyl chloride with AlCl3
Explanation: Anthracene is synthesized by AlCl3-catalyzed condensation of two benzyl chloride molecules.
67.Elbs reaction involves pyrolysis of which compound to give anthracene?
a) O-methyl benzophenone
b) Benzyl chloride
c) Benzene
d) Naphthalene
Answer: a) O-methyl benzophenone
Explanation: Pyrolysis of O-methyl benzophenone at 450°C yields anthracene via the Elbs reaction.
68.Diels-Alder reaction of anthracene occurs at:
a) 1,2-positions
b) 9,10-positions
c) 4,5-positions
d) Multiple positions equally
Answer: b) 9,10-positions
Explanation: Anthracene acts as a diene, reacting at the 9,10 positions to form Diels-Alder adducts.
69.Anthracene oxidation with sodium dichromate produces:
a) Anthraquinone
b) Phenanthraquinone
c) Diphenic acid
d) Phthalic anhydride
Answer: a) Anthraquinone
Explanation: Oxidation of anthracene yields 9,10-anthraquinone, a key intermediate in dye synthesis.
70.Anthracene reduction with sodium and ethyl alcohol forms:
a) 9,10-Dihydroanthracene
b) Anthrol
c) Tetralin
d) Diphenylanthracene
Answer: a) 9,10-Dihydroanthracene
Explanation: Sodium/ethyl alcohol selectively reduces anthracene at the 9,10 positions, producing dihydro derivatives.
71.Anthracene undergoes dimerization under:
a) Visible light
b) UV light
c) Infrared radiation
d) Heat only
Answer: b) UV light
Explanation: UV light induces dimerization of anthracene to form dianthracene.
72.Anthracene glycosides exhibit which pharmacological activity?
a) Laxative and cathartic
b) Anti-inflammatory
c) Antiviral
d) Antihistaminic
Answer: a) Laxative and cathartic
Explanation: Oxygenated derivatives of anthracene, such as anthracene glycosides, are used as laxatives.
73.Which natural anthracene derivative has hepatoprotective activity?
a) Rhein
b) Emodin
c) Aloe-emodin
d) Chrysophanol
Answer: a) Rhein
Explanation: Rhein shows hepatoprotective and antioxidant effects.
74.Anthracene is insoluble in:
a) Benzene
b) Water
c) Ether
d) Alcohol
Answer: b) Water
Explanation: Anthracene is non-polar and insoluble in water but dissolves in organic solvents.
75.Anthracene’s melting point is approximately:
a) 150 °C
b) 218 °C
c) 100 °C
d) 300 °C
Answer: b) 218 °C
Explanation: Anthracene melts at around 218 °C.
76.Which anthracene derivative is used as a laxative?
a) Dioxyanthracene
b) Anthrone
c) Anthraquinone
d) Emodin
Answer: d) Emodin
Explanation: Emodin is an anthracene derivative with cathartic and laxative properties.
77.Anthracene’s fluorescence property is utilized in:
a) Forensics and dye manufacturing
b) Food preservatives
c) Plastic additives
d) Pesticides
Answer: a) Forensics and dye manufacturing
Explanation: Its strong fluorescence under UV light has applications in forensics and dyes.
78.Anthracene acetylation in non-polar solvents at low temperature yields:
a) 9-acetylanthracene
b) 1-acetylanthracene
c) 2-acetylanthracene
d) 4-acetylanthracene
Answer: a) 9-acetylanthracene
Explanation: Acetylation favors the 9-position in non-polar solvents at low temperatures.
79.Which statement about anthracene is FALSE?
a) Anthracene has a planar structure
b) Anthracene is more aromatic than benzene
c) Electrophilic substitution occurs mainly at 9,10-positions
d) Anthracene shows blue fluorescence under UV light
Answer: b) Anthracene is more aromatic than benzene
Explanation: Anthracene is less aromatic than benzene, with lower resonance energy per ring.
80.Which compound has a planar structure with three fused benzene rings arranged linearly?
a) Phenanthrene
b) Anthracene
c) Triphenylmethane
d) Diphenylmethane
Answer: b) Anthracene
Explanation: Anthracene’s three benzene rings are linearly fused in a planar fashion.
81.Which polynuclear aromatic hydrocarbon is used in forensic detection due to fluorescence?
a) Naphthalene
b) Anthracene
c) Diphenylmethane
d) Triphenylmethane
Answer: b) Anthracene
Explanation: Anthracene fluoresces strongly under UV light, useful in forensic applications.
82.Which polynuclear aromatic hydrocarbon is used for dye precursor production such as alizarin?
a) Anthracene
b) Naphthalene
c) Phenanthrene
d) Triphenylmethane
Answer: a) Anthracene
Explanation: Anthracene derivatives like anthraquinone are precursors for alizarin dye manufacture.
83.Which compound exhibits blue fluorescence under UV light?
a) Anthracene
b) Triphenylmethane
c) Diphenylmethane
d) Naphthalene sulfonic acid
Answer: a) Anthracene
Explanation: Anthracene is known for its characteristic blue fluorescence.
84.The photochemical dimerization of anthracene occurs at:
a) 1,2-positions
b) 9,10-positions
c) 4,5-positions
d) 2,3-positions
Answer: b) 9,10-positions
Explanation: Anthracene dimerizes on UV exposure at the 9,10 positions, forming dianthracene.
85.Which PAH derivatives are used in laxative formulations?
a) Anthracene
b) Triphenylmethane
c) Diphenylmethane
d) Phenanthrene
Answer: a) Anthracene
Explanation: Anthracene glycosides are known laxatives.
86.Which PAH is mainly susceptible to oxidative degradation?
a) Anthracene
b) Diphenylmethane
c) Triphenylmethane
d) Phenanthrene
Answer: a) Anthracene
Explanation: Anthracene can be readily oxidized to anthraquinone.
87.Anthracene can undergo Diels-Alder reactions due to:
a) Its conjugated diene system at 9,10-positions
b) Presence of hydroxyl groups
c) Halogen substituents
d) Its saturated nature
Answer: a) Its conjugated diene system at 9,10-positions
Explanation: The central ring’s 9,10-double bonds allow diene reactivity.
88.Diphenylmethane consists of:
a) Three fused benzene rings
b) Two benzene rings joined by a methylene group
c) Three benzene rings in a linear chain
d) Benzene ring attached to a cyclohexane
Answer: b) Two benzene rings joined by a methylene group
Explanation: The core of diphenylmethane is two phenyl rings attached to a central methylene (-CH₂-) group.
89.Diphenylmethane is used in the synthesis of:
a) Beta blockers
b) Luminogens for aggregation-induced emission
c) Cardiac glycosides
d) Synthetic rubber
Answer: b) Luminogens for aggregation-induced emission
Explanation: It is described as widely used for this application.
90.The molecular formula of diphenylmethane is:
a) C12H10
b) C13H12
c) C14H12
d) C14H10
Answer: c) C14H12
Explanation: Diphenylmethane consists of two phenyl groups attached to a methylene (-CH2-) group, with the total formula C14H12.
91.Diphenylmethane is prepared by reduction of which compound?
a) Diphenylketone (benzophenone)
b) Benzophenone oxide
c) Diphenyl ether
d) Benzyl chloride
Answer: a) Diphenylketone (benzophenone)
Explanation: Reduction of benzophenone by hydrogen and a catalyst forms diphenylmethane.
92.Diphenylmethyl potassium is used in:
a) Organic polymerization
b) Anticancer drug synthesis
c) Dye makingd) Perfume production
Answer: a) Organic polymerization
Explanation: This organopotassium compound is important in polymerization reactions.
93.Which of the following is a derivative of diphenylmethane?
a) Benzhydrol
b) Benzene
c) Aniline
d) Phthalic anhydride
Answer: a) Benzhydrol
Explanation: Benzhydrol (diphenylmethanol) is a common diphenylmethane derivative.
94.Diphenylmethane is:
a) A white crystalline solid
b) A colorless oil
c) A green powder
d) A yellow liquid
Answer: a) A white crystalline solid
Explanation: Diphenylmethane appears as a white solid under standard conditions.
95.Diphenylmethane is soluble in:
a) Water
b) Organic solvents like benzene and ether
c) Acidic solutions only
d) Basic solutions only
Answer: b) Organic solvents like benzene and ether
Explanation: Non-polar diphenylmethane dissolves in organic solvents but not water.
96.Which polynuclear hydrocarbon has the greatest solubility in organic solvents?
a) Phenanthrene
b) Diphenylmethane
c) Anthracene
d) Naphthalene
Answer: b) Diphenylmethane
Explanation: Diphenylmethane’s non-fused aromatic rings give it better solubility in organic solvents.
97.Diphenylmethane serves as an intermediate in the synthesis of:
a) Aggregation-induced emission luminogens
b) Antibiotics
c) Vitamins
d) Plasticizers
Answer: a) Aggregation-induced emission luminogens
Explanation: Diphenylmethane is a building block for compounds exhibiting aggregation-induced emission.
98.Diphenylmethane can be converted to benzophenone by:
a) Oxidation
b) Reduction
c) Halogenation
d) Hydrolysis
Answer: a) Oxidation
Explanation: Diphenylmethane oxidizes to benzophenone under strong oxidizing conditions.
99.Which compound contains a methylene bridge between phenyl groups?
a) Diphenylmethane
b) Triphenylmethane
c) Naphthalene
d) Anthracene
Answer: a) Diphenylmethane
Explanation: Diphenylmethane has two phenyls linked by a methylene group.
100.Triphenylmethane is the chromogen of:
a) Dyes
b) Antimalarials
c) Stimulant drugs
d) Pesticides
Answer: a) Dyes
Explanation: Crystal violet, gentian violet, aurin, and malachite green are key dyes based on this nucleus.
101.The molecular formula of triphenylmethane is:
a) C19H16
b) C20H16
c) C21H18
d) C18H15
Answer: a) C19H16
Explanation: Three phenyl groups attached to a central carbon results in C19H16.
102.Triphenylmethane dyes are characterized by:
a) Poor color intensity
b) Brilliant colors with poor lightfastness
c) No solubility in organic solvents
d) Non-aromatic nature
Answer: b) Brilliant colors with poor lightfastness
Explanation: They produce intense colors but fade quickly under light.
103.Triphenylmethane is synthesized by:
a) Condensation of benzene with chloroform in presence of AlCl3
b) Reduction of triphenylcarbinol
c) Friedel-Crafts acylation of benzene
d) Diels-Alder reaction
Answer: a) Condensation of benzene with chloroform in presence of AlCl3
Explanation: Friedel-Crafts alkylation of benzene with chloroform and AlCl3 yields triphenylmethane.
104.Which dye is a derivative of triphenylmethane?
a) Crystal violet
b) Indigo
c) Alizarin
d) Malachite green
Answer: a) Crystal violet and d) Malachite green
Explanation: Both are dyes based on the triphenylmethane chromophore.
105.Triphenylmethane crystal violet is used in:
a) Textile dyeing
b) Botanical medications
c) Paper coloring and typewriter ribbons
d) Water purification
Answer: c) Paper coloring and typewriter ribbons
Explanation: Crystal violet is widely used in printing inks and ribbons.
106.Which auxochromes are commonly found in triphenylmethane dyes?
a) –OH, –NH2, –NR2
b) –NO2, –CN, –COOH
c) –F, –Cl, –Br
d) –CH3, –C2H5
Answer: a) –OH, –NH2, –NR2
Explanation: These groups enhance color intensity by resonance in dyes.
107.Triphenylmethane dyes fade rapidly due to:
a) Poor solubility
b) Photodegradation caused by sunlight
c) High melting points
d) High pH sensitivity
Answer: b) Photodegradation caused by sunlight
Explanation: They exhibit poor lightfastness and degrade when exposed to sunlight.
108.Malachite green, a triphenylmethane dye, is used as:
a) Antimicrobial agent
b) Textile dye
c) Food preservative
d) Plasticizer
Answer: a) Antimicrobial agent and b) Textile dye
Explanation: It has applications in dyeing and antimicrobial treatments.
109.Triphenylmethane dyes are mostly used in:
a) Textile industry
b) Typewriter ribbons and paper coloring
c) Plastic manufacturing
d) Pharmaceutical formulations
Answer: b) Typewriter ribbons and paper coloring
Explanation: Due to limited lightfastness, their main use is in products with limited light exposure.
110.Triphenylmethane derivatives primarily serve as:
a) Antimicrobial drugs
b) Synthetic dyes
c) Analgesics
d) Biological fertilizers
Answer: b) Synthetic dyes
Explanation: The triphenylmethane nucleus forms the core of many commercially important synthetic dyes.
111.Which compound is used in the preparation of dyes such as crystal violet and aurin?
a) Triphenylmethane
b) Phenanthrene
c) Diphenylmethane
d) Anthracene
Answer: a) Triphenylmethane
Explanation: The triphenylmethane core is involved in preparing these dyes.
112.Triphenylmethane-based dyes display color due to:
a) Extended conjugation of the central carbon with phenyl rings
b) Presence of nitro groups
c) Alkyl substitution on the rings
d) Lack of conjugation
Answer: a) Extended conjugation of the central carbon with phenyl rings
Explanation: Color arises from resonance and conjugation in triphenylmethane dyes.
113.Which of the following PAHs is known for causing skin photosensitivity?
a) Anthracene
b) Phenanthrene
c) Diphenylmethane
d) Triphenylmethane
Answer: b) Phenanthrene
Explanation: Phenanthrene is known to sensitize skin to sunlight.
114.Which PAH is most volatile and exists partly in the gaseous phase in the environment?
a) Naphthalene
b) Anthracene
c) Phenanthrene
d) Triphenylmethane
Answer: a) Naphthalene
Explanation: Lower molecular weight naphthalene shows some vapor pressure and can exist in the gas phase.
115.Which of the following is NOT a typical chemical property of polycyclic aromatic hydrocarbons?
a) Lipophilicity
b) High aqueous solubility
c) Persistence in the environment
d) Nonpolar nature
Answer: b) High aqueous solubility
Explanation: PAHs are generally poorly soluble in water.
116.Which poison is primarily derived from polycyclic aromatic hydrocarbons?
a) Benzene
b) Polycyclic aromatic hydrocarbons (PAHs) from coal tar
c) Chlorinated phenols
d) Alkyl halides
Answer: b) Polycyclic aromatic hydrocarbons (PAHs) from coal tar
Explanation: PAHs are toxic and carcinogenic components from coal tar.
117.Which PAHs are found in tobacco smoke and have carcinogenic properties?
a) Phenanthrene and naphthalene
b) Diphenylmethane only
c) Triphenylmethane only
d) None of the above
Answer: a) Phenanthrene and naphthalene
Explanation: Both are PAHs with mutagenic and carcinogenic effects.
118.Haworth synthesis is used mainly to synthesize:
a) Diphenylmethane
b) Naphthalene and phenanthrene
c) Triphenylmethane
d) Anthracene sulfonic acids
Answer: b) Naphthalene and phenanthrene
Explanation: Haworth synthesis is a classical route for making these PAHs
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