78 practice questions on Haloalkanes & Haloarenes , sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Haloalkanes & Haloarenes notes .
SN2: one step Nu- C X- backside attack ↓ Nu C + X- Inversion of configuration (Walden inversion) SN1: two steps C X- slow: leaving group exits ↓ + C carbocation Nu- Planar intermediate gives racemisation (both faces attacked) SN2 proceeds in a single step with backside attack and inversion of configuration, while SN1 forms a planar carbocation intermediate first, leading to racemisation.
Easy - 26 questions Q2.
The carbon atom bonded to the halogen in a saturated haloalkane is:
A sp hybridisedB sp3 hybridisedC sp2 hybridisedD sp3 d hybridisedShow answer & explanation →
Q3.
Which of the following is a gem-dihalide (both halogens on the same carbon)?
A 1,2-dichloroethaneB 1,3-dichloropropaneC 1,1-dichloroethaneD 1,4-dichlorobutaneShow answer & explanation →
Q4.
Chloroform is stored in dark bottles filled to the brim because on exposure to air and light it slowly forms:
A chlorobenzeneB mustard gasC chloropicrinD phosgeneShow answer & explanation →
Q5.
Which chloromethane, once marketed as pyrene, was formerly used as a fire extinguisher?
A CCl4 B CH2 Cl2 C CHI3 D CHCl3 Show answer & explanation →
Q6.
What is the functional group present in haloalkanes?
A Hydroxyl (-OH) in typical laboratory settingsB Amino (-NH2 ) under usual circumstancesC Carbon-halogen bond (C-X)D Carbonyl (C=O) according to most researchersShow answer & explanation →
Q7.
Which reagent is used to convert an alcohol into an alkyl halide with retention of configuration?
A HClB PCl5 C SOCl2 D ZnCl2 /HClShow answer & explanation →
Q8.
In a primary haloalkane, the halogen is attached to a carbon bonded to:
A Three other carbon atomsB Two other carbon atomsC One other carbon atomD No other carbon atomShow answer & explanation →
Q9.
Which of the following is the IUPAC name for CH3 CH2 Br?
A Methyl bromideB BromoethaneC Ethyl bromideD 1-bromoethaneShow answer & explanation →
Q10.
The Finkelstein reaction converts an alkyl chloride to an alkyl iodide using:
A AgF in MeOHB NaI in dry acetoneC KBr in waterD HI gasShow answer & explanation →
Q11.
The C-X bond length order in haloalkanes is:
A C-F < C-Cl < C-Br < C-IB C-I < C-Br < C-Cl < C-FC C-F = C-Cl = C-Br = C-ID C-Cl < C-F < C-Br < C-IShow answer & explanation →
Q13.
In SN2 reactions, the nucleophile attacks:
A From the same side as the leaving groupB From the opposite side to the leaving groupC From the top onlyD From a random directionShow answer & explanation →
Q14.
The boiling point of haloalkanes compared to the parent alkane of similar molar mass is:
A Much lowerB SimilarC The sameD HigherShow answer & explanation →
Q15.
DDT is harmful to the environment because it is:
A A strongly corrosive mineral-type acid that damages plant tissueB A non-biodegradable persistent organic pollutantC A compound that readily dissolves in water and washes away harmlesslyD An emitter of ionising radiation that damages cellular DNAShow answer & explanation →
Q16.
What type of bond does a Grignard reagent (RMgX) contain?
A Polar covalent C-Mg bond with C acting as nucleophileB A largely ionic bond between a carbanion and the magnesium cationC A non-polar covalent bond identical to a C-C bond in alkanesD A mainly dative bond donated from magnesium toward the carbon atomShow answer & explanation →
Q17.
The reactivity of haloalkanes toward SN2 reaction follows the order:
A 3° > 2° > 1°B 1° > 2° > 3°C 2° > 1° > 3°D All are equalShow answer & explanation →
Q18.
Which solvent favours the SN2 mechanism?
A Water in the majority of cases studiedB Ethanol as widely reportedC Dimethylformamide (DMF)D Acetic acid in standard practiceShow answer & explanation →
Q19.
The addition of HBr to propene in the absence of peroxides gives:
A 1-bromopropane (anti-Markovnikov)B 2-bromopropane (Markovnikov)C 1,2-dibromopropaneD Propyl bromide mixtureShow answer & explanation →
Q20.
Freons are used as refrigerants but are harmful because they:
A React with atmospheric water vapour to generate hydrochloric acid directlyB Release chlorine radicals that catalytically destroy the ozone layerC Are acutely toxic to humans even at very low inhaled concentrationsD Dissolve readily in rainwater, directly causing acid rain over citiesShow answer & explanation →
Q21.
In the SN1 mechanism, the rate of the reaction depends on:
A Both substrate and nucleophile concentrationB Only nucleophile concentrationC Only substrate concentrationD Temperature onlyShow answer & explanation →
Q22.
Dehydrohalogenation of an alkyl halide with KOH/alcohol gives:
A AlcoholB AlkaneC Carboxylic acidD AlkeneShow answer & explanation →
Q23.
A compound that rotates the plane of polarised light is said to be:
A Aromatic under most conditions encounteredB Optically activeC Racemic as frequently observed in practiceD Achiral in many documented casesShow answer & explanation →
Q24.
The Swarts reaction is used to prepare:
A Alkyl fluorides from alkyl chlorides using AgFB Alkyl iodides from alkyl chlorides using NaIC Alkyl bromides from alkyl chlorides using NaBrD Alkyl chlorides from alkenes using HClShow answer & explanation →
Q25.
The bond strength order in haloalkanes is:
A C-F > C-Cl > C-Br > C-IB C-I > C-Br > C-Cl > C-FC C-Cl > C-F > C-Br > C-ID C-Br > C-I > C-F > C-ClShow answer & explanation →
Q26.
Nitration of chlorobenzene gives mainly which products?
A Only the meta isomerB Equal amounts of all three isomersC Only the meta and para isomersD The ortho and para isomersShow answer & explanation →
Medium - 26 questions Q27.
The correct order of reactivity of alkyl halides towards the SN 1 reaction is:
A methyl > 1° > 2° > 3°B 3° > 2° > 1° > methylC 1° > 2° > 3° > methylD 2° > 3° > 1° > methylShow answer & explanation →
Q28.
When 2-bromopropane is boiled with alcoholic KOH, the major product is:
A propan-2-olB propan-1-olC propeneD propaneShow answer & explanation →
Q29.
Chlorobenzene is far less reactive than chloromethane toward nucleophilic substitution mainly because:
A chlorine shows a strong +I inductive effect hereB the benzene ring sterically blocks the nucleophileC chlorobenzene has a much higher boiling pointD the C-Cl bond has partial double-bond characterShow answer & explanation →
Q30.
Chlorobenzene reacting with chloral (trichloroacetaldehyde) in the presence of sulfuric acid yields:
A DDT (a persistent insecticide)B BHC (benzene hexachloride)C Freon-12 (a refrigerant)D chloroform (an anaesthetic)Show answer & explanation →
Q31.
The Wurtz-Fittig reaction of an aryl halide with an alkyl halide and sodium in dry ether gives:
A a biarylB an alkylareneC a symmetrical etherD an alkaneShow answer & explanation →
Q32.
The SN1 reaction of (R)-2-bromobutane with dilute NaOH gives:
A Mainly the (R)-2-butanol product with complete retention of configurationB Mainly the (S)-2-butanol product via complete inversion of configurationC A racemic mixture of (R)- and (S)-2-butanolD No observable reaction since dilute NaOH cannot attack a secondary halideShow answer & explanation →
Q34.
The reaction of chlorobenzene with sodium hydroxide under severe conditions (300°C, high pressure) gives:
A BenzeneB PhenolC AnilineD BenzaldehydeShow answer & explanation →
Q35.
Which of the following best explains why vinyl chloride (CH2 =CHCl) is much less reactive than ethyl chloride (C2 H5 Cl) toward SN2 reactions?
A Vinyl C-Cl bond has partial double-bond character due to resonance; the Cl lone pair delocalises into the ring making the bond shorter and strongerB Vinyl chloride generally happens to possess a noticeably higher overall molar mass than ethyl chloride does according to standard textbooks in general practiceC Vinyl chloride happens to exist as an ordinary liquid rather than as a gas under normal room conditions as frequently described in most textbook accountsD The chlorine atom in vinyl chloride is in fact attached at a secondary rather than primary carbon position during normal conditions as generally observedShow answer & explanation →
Q36.
When 2-bromo-2-methylpropane reacts with NaOEt (sodium ethoxide) in ethanol, the major product is:
A 2-methyl-1-propanol in typical laboratory settingsB 2-methylpropene (Zaitsev product)C 2-ethoxy-2-methylpropane under usual circumstancesD 1-bromo-2-methylpropane according to most researchersShow answer & explanation →
Q38.
The reaction of a Grignard reagent (RMgBr) with CO2 followed by hydrolysis gives:
A An alcoholB A ketoneC An esterD A carboxylic acidShow answer & explanation →
Q39.
Which of the following haloalkanes is most reactive toward the SN2 mechanism?
A (CH3 )3CBrB (CH3 )2CHBrC CH3 CH2 BrD CH3 BrShow answer & explanation →
Q40.
In the reaction: R-X + KCN → R-CN, which type of reaction is this?
A SN1 substitutionB SN2 substitutionC EliminationD Electrophilic substitutionShow answer & explanation →
Q41.
The order of reactivity of halogens in haloarenes toward electrophilic aromatic substitution (directing ability) is:
A F > Cl > Br > I (ortho/para directors despite being deactivating)B I > Br > Cl > F, the reverse order of true ortho/para directing strengthC Substitution occurring preferentially through the meta position insteadD Haloarenes failing to undergo electrophilic aromatic substitution entirelyShow answer & explanation →
Q42.
What is the product of the reaction between benzyl bromide (C6 H5 CH2 Br) and aqueous NaOH?
A Chlorobenzene in the majority of cases studiedB Benzaldehyde as widely reportedC Benzyl alcohol (C6 H5 CH2 OH)D Phenol in standard practiceShow answer & explanation →
Q43.
The reaction of an alkyl halide RX with Mg in dry ether gives a Grignard reagent. This reaction fails if:
A The solvent is dry etherB Excess Mg is usedC Moisture or oxygen is presentD The alkyl halide is primaryShow answer & explanation →
Q44.
Which of the following reactions does NOT occur for haloarenes under mild conditions?
A Electrophilic aromatic substitution occurring readily on the aromatic ringB Reaction with dry Mg in ether to form an aryl Grignard reagentC Catalytic reduction with H2 over Pd to give the parent benzene ringD Nucleophilic substitution at room temperature with dilute NaOHShow answer & explanation →
Q45.
The optical rotation of a racemic mixture is:
A +180°, indicating a single pure dextrorotatory enantiomer is presentB -180°, indicating a single pure levorotatory enantiomer is presentC 0° (optically inactive)D A variable value that changes randomly each time it is measuredShow answer & explanation →
Q46.
Which halide undergoes nucleophilic substitution most readily?
A Fluoride (C-F)B Chloride (C-Cl)C Bromide (C-Br)D Iodide (C-I)Show answer & explanation →
Q47.
A compound has the formula C3 H7 Cl and shows optical isomerism. The compound is:
A 1-chloropropaneB 2-chloropropaneC 3-chloropropaneD Both 1- and 3-chloropropaneShow answer & explanation →
Q48.
In Nucleophilic Substitution, a polar protic solvent stabilises the leaving group (anion) but also stabilises the nucleophile. Its overall effect on SN2 rate compared to polar aprotic solvent is:
A Rate is much faster in polar protic solvent because the leaving group is destabilised insteadB Rate is slower in polar protic solvent because the nucleophile is heavily solvated and less reactiveC The rate stays exactly identical regardless of which solvent type is chosenD Polar protic solvent always forces the mechanism to switch completely from SN2 to SN1Show answer & explanation →
Q49.
The reaction of chlorobenzene with Cl2 in the presence of FeCl3 gives mainly:
A 1,3-dichlorobenzene (meta), formed because chlorine is a meta director hereB Hexachlorobenzene, formed via complete substitution of all six ring positionsC Chlorocyclohexane, formed by saturation of the aromatic ring with chlorineD 1,4-dichlorobenzene (para) and 1,2-dichlorobenzene (ortho) as major productsShow answer & explanation →
Q50.
The relative rate of solvolysis (SN1) of tertiary butyl chloride compared to primary butyl chloride in aqueous ethanol is:
A Primary is faster, since SN1 solvolysis favours less hindered substratesB Both rates are essentially equal under these solvolysis conditionsC Tertiary is faster by approximately 106 timesD Tertiary is only modestly faster, by roughly a factor of 2Show answer & explanation →
Q51.
Which of the following is the correct statement about the dipole moment of chlorobenzene versus cyclohexyl chloride?
A Chlorobenzene has a higher dipole moment because resonance enhances the C-Cl bond polarityB Cyclohexyl chloride has a higher dipole moment due to no resonance reduction of the C-Cl dipoleC Both compounds show exactly equal dipole moments within experimental errorD Neither compound shows any measurable dipole moment at allShow answer & explanation →
Q52.
Chlorine deactivates the benzene ring, yet it directs an incoming group to the ortho and para positions. This is because:
A resonance controls reactivity while the inductive effect controls orientationB the inductive effect controls reactivity while resonance controls orientationC both reactivity and orientation are controlled by the inductive effectD both reactivity and orientation are controlled by resonanceShow answer & explanation →
Hard - 26 questions Q53.
o- and p-nitrochlorobenzene undergo substitution with NaOH more readily than chlorobenzene because the nitro group:
A lengthens the carbon-chlorine bondB increases the electron density of the ringC stabilises the anionic intermediate by resonanceD acts as a strong electron-donating groupShow answer & explanation →
Q54.
The correct order of dipole moment among the halomethanes is:
A CH3 F > CH3 Cl > CH3 Br > CH3 IB CH3 I > CH3 Br > CH3 Cl > CH3 FC CH3 Br > CH3 Cl > CH3 F > CH3 ID CH3 Cl > CH3 F > CH3 Br > CH3 IShow answer & explanation →
Q55.
Dehydrohalogenation of 2-bromo-2-methylbutane with alcoholic KOH gives, as the major product:
A 2-methylbut-2-eneB 2-methylbut-1-eneC 3-methylbut-1-eneD 2-methylbutan-1-olShow answer & explanation →
Q56.
A polar aprotic solvent such as DMF or DMSO speeds up an SN 2 reaction because:
A it solvates the nucleophile very stronglyB it solvates the cation, freeing the nucleophileC it hydrogen-bonds tightly to the nucleophileD it lowers the nucleophile concentration sharplyShow answer & explanation →
Q57.
When optically active 2-bromooctane is hydrolysed under SN 1 conditions, the product is:
A a single product with full retentionB a single product with full inversionC a largely racemised mixtureD an achiral meso productShow answer & explanation →
Q58.
Predict the product when (S)-2-bromobutane undergoes SN2 reaction with NaOH:
A (R)-2-butanol due to inversion of configurationB (S)-2-butanol with retention of configuration at the stereocentreC A fully racemic mixture of (R)- and (S)-2-butanolD A mixture of butene isomers formed via E2 elimination insteadShow answer & explanation →
Q59.
Which of the following statements correctly explains the Menshutkin reaction?
A A tertiary amine reacts with an alkyl halide via SN2 to give a quaternary ammonium salt (R3N + RX → R3NR+ X-)B A primary amine undergoes an SN1 solvolysis with a tertiary alkyl halide under typical conditions according to standard textbooksC A secondary amine generally reacts with HCl gas to form an ammonium chloride salt in general practice as frequently describedD A quaternary ammonium salt undergoes Hofmann elimination to give an alkene in most textbook accounts during normal conditionsShow answer & explanation →
Q60.
In the reaction of 2-bromo-2-methylbutane with EtOH, the major and minor alkene products follow which rule?
A Hofmann rule: less substituted alkene is majorB Zaitsev rule: more substituted alkene (2-methyl-2-butene) is majorC Exactly equal amounts of both possible alkene isomers formD No elimination occurs at all under these solvolysis conditionsShow answer & explanation →
Q61.
In nucleophilic aromatic substitution (SNAr) on 2,4-dinitrochlorobenzene, the mechanism involves:
A A simple SN2 backside attack directly on the sp2 ring carbon bearing chlorine as generally observedB Formation of a Meisenheimer complex (carbanion intermediate) followed by departure of Cl-C A free radical chain mechanism initiated by homolytic C-Cl cleavage in typical laboratory settingsD A carbocation (arenium ion) intermediate, as seen in electrophilic substitution under usual circumstancesShow answer & explanation →
Q62.
The Ramberg-Backlund reaction converts an alpha-halo sulfone to an alkene. Which of the following best describes the key step?
A SN2 attack by the alpha-carbanion on the alpha carbon bearing the leaving group, forming a three-membered ring (episulfone) that extrudes SO2 B A perfectly ordinary E2 elimination occurring directly across the adjacent alpha and beta carbon atoms according to most researchers in the majority of cases studiedC A straightforward free radical chain process that is propagated continuously by sulfonyl radicals as widely reported in standard practiceD An SN1-type ionisation of the sulfone substrate followed by a subsequent carbocation rearrangement step under most conditions encounteredShow answer & explanation →
Q63.
Which of the following is the correct order of leaving group ability?
A F- > Cl- > Br- > I-B OH- > F- > Cl- > Br-C Br- > I- > Cl- > F-D I- > Br- > Cl- > F-Show answer & explanation →
Q64.
The SN2 reaction has a second-order rate law. If the concentration of both the substrate (RX) and the nucleophile (Nu) are each doubled, the rate:
A DoublesB QuadruplesC Remains the sameD Increases 8-foldShow answer & explanation →
Q65.
Why does the Gabriel synthesis give only primary amines?
A Potassium phthalimide is used; after SN2 alkylation and hydrazinolysis, only primary amines form because the phthalimide N can only be monoalkylatedB The whole synthesis is mechanistically restricted to working mainly with primary alkyl halide substrates as frequently observed in practice in many documented casesC The intermediate's acidic hydrolysis happens to fortuitously halt precisely at the primary amine stage according to conventional understandingD The Gabriel synthesis is said to work mainly for preparing aromatic primary amines instead in routine practice overall in most cases under typical conditionsShow answer & explanation →
Q66.
The E2 elimination of (2R,3S)-2-bromo-3-phenylbutane gives predominantly:
A trans (E)-2-phenyl-2-butene, formed from the corresponding diastereomeric bromide insteadB An equal mixture of cis and trans alkenes regardless of stereochemistryC Only the terminal alkene 1-phenyl-2-butene via a different elimination pathwayD cis (Z)-2-phenyl-2-butene due to anti periplanar arrangement requirementShow answer & explanation →
Q67.
Allylic halides are much more reactive than primary alkyl halides toward SN1. This is because:
A The allylic carbocation formed is resonance-stabilised by delocalisation over three carbonsB Allylic halides generally possess a weaker, more easily broken carbon-halogen bond according to standard textbooksC Allylic halides are structurally usually tertiary alkyl halides in general practice as frequently describedD Resonance stabilisation does not apply to carbocation intermediates in most textbook accountsShow answer & explanation →
Q68.
Identify the product when 1-bromo-2-methylpropane (isobutyl bromide) reacts with Na/K metal (Wurtz reaction) with the same compound:
A 2-methylpropane, formed instead by a simple reductive removal of the bromine atom from each molecule, with highly no carbon-carbon coupling occurring between the two separate alkyl fragments involved during normal conditions as generally observedB 2,4-dimethylhexane (2,4-dimethylbutane is wrong; the correct product is 2,4-dimethylhexane but isobutyl gives 2,4-dimethylbutane... actually 2,6-dimethylbutane is not possible; Wurtz gives 2,2,4-trimethylpentane for 2-methyl-1-bromopropane)C Propene, formed instead by a competing base-induced elimination pathway that largely outcompetes the intended Wurtz coupling reaction step under these conditions in typical laboratory settings under usual circumstances according to most researchersD Isobutane, formed instead by a simple hydrogen atom abstraction step from the solvent rather than by any carbon-carbon coupling reaction step in the majority of cases studied as widely reported in standard practice under most conditions encounteredShow answer & explanation →
Q69.
Which of the following pairs of compounds are enantiomers?
A (R)-2-chlorobutane and (S)-2-chlorobutaneB (R)-2-chlorobutane and (R)-2-chlorobutaneC Meso-2,3-dichlorobutane and (R,R)-2,3-dichlorobutaneD 1-chlorobutane and 2-chlorobutaneShow answer & explanation →
Q70.
When 1,2-dibromoethane is treated with Zn metal, the product is:
A Ethane, formed by simple reductive removal of both bromine atoms with hydrogenB Ethene (elimination of both Br via zinc)C 1,2-ethanediol, formed by hydrolytic substitution of both bromine atomsD Zinc bromide only, with no organic product formed in the reactionShow answer & explanation →
Q71.
The rate of solvolysis of benzyl chloride (C6 H5 CH2 Cl) compared to n-propyl chloride is:
A Slower due to aromatic stabilisation of the starting chloride itselfB Essentially the same rate as observed for n-propyl chlorideC Only modestly faster, by a small and chemically insignificant marginD Much faster because the benzylic carbocation is resonance-stabilisedShow answer & explanation →
Q72.
In the Ullmann reaction, two aryl halides are coupled in the presence of copper to give:
A A biaryl (Ar-Ar)B A phenolC An aryl amineD An aryl ketoneShow answer & explanation →
Q73.
Mustard gas [ClCH2 CH2 SCH2 CH2 Cl, sulfur mustard] alkylates DNA because:
A It undergoes intramolecular cyclisation forming a highly reactive sulfonium ion (ethylenesulfonium) that acts as an alkylating agent via SN1B It is generally a strong Bronsted acid that directly protonates the nucleophilic nitrogen atoms found within DNA bases as frequently observed in practiceC It rapidly eliminates hydrochloric acid to generate a reactive vinyl sulfide intermediate that then attacks DNA in many documented casesD It reacts with the DNA backbone through an largely sulfur-centred free radical chain propagation mechanism according to conventional understandingShow answer & explanation →
Q74.
For a compound to be optically active it must be:
A Chiral and not superimposable on its mirror imageB Contain an even number of chiral centres in routine practiceC Have a meso form overall in most cases under typical conditionsD Contain mainly carbon and hydrogen according to standard textbooksShow answer & explanation →
Q75.
Which of the following correctly describes the fate of the free radical Cl• in the stratosphere with respect to ozone?
A Cl• + O3 → ClO• + O2 ; then ClO• + O• → Cl• + O2 ; the Cl• is regenerated catalytically destroying thousands of O3 moleculesB Cl• directly and largely irreversibly reacts with atmospheric N2 gas to permanently form nitrogen trichloride during normal conditionsC Cl• is mostly consumed by forming stable HCl gas with little further ozone destruction occurring afterward, as generally observedD Cl• reacts harmlessly with O2 gas to form a fairly stable, largely unreactive ClO2 species in typical laboratory settingsShow answer & explanation →
Q76.
Which of the following is a correct statement about nucleophilicity versus basicity?
A Nucleophilicity is a kinetic property (rate of attack on carbon); basicity is a thermodynamic property (affinity for proton); a good base is not necessarily a good nucleophileB Nucleophilicity and basicity are in fact fundamentally the very same underlying property, just measured using different units in general practice as frequently describedC Strong Bronsted bases are said to rarely simultaneously be capable of acting as effective nucleophiles in any solvent in most textbook accounts during normal conditions as generally observedD The iodide ion is actually said to be a noticeably stronger Bronsted base toward a proton than the fluoride ion is in typical laboratory settings under usual circumstancesShow answer & explanation →
Q77.
The Reimer-Tiemann reaction is not applicable to haloalkanes because:
A Haloalkanes generally cannot be mixed safely with chloroform and aqueous base together according to most researchersB The reaction requires a phenolic substrate; haloalkanes lack the activating -OH group on an aromatic ringC Haloalkanes are far too chemically reactive to survive the reaction conditions in the majority of cases studiedD Haloalkanes fail to dissolve in the aqueous sodium hydroxide solution used as widely reported in standard practiceShow answer & explanation →
Q78.
Which reagents bring about Friedel–Crafts acylation of chlorobenzene?
A CH3 COOH with conc. H2 SO4 B CH3 CHO with dilute NaOHC CH3 COCl with anhydrous AlCl3 D CH3 COONa with soda limeShow answer & explanation →