NEET UG Haloalkanes and Haloarenes — practice questions
96 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice NEET UG Haloalkanes and Haloarenes in the app →The C–X bond enthalpies follow the order:Among alkyl halides, the order of reactivity towards nucleophilic substitution (for the same R group) is:Which of the following reagents is preferred for converting an alcohol R-OH into an alkyl chloride because theThe order of reactivity of alcohols with a given haloacid (HCl, HBr, HI) is:The reaction of alkyl chloride/bromide with NaI in dry acetone to form alkyl iodide is called:Among methyl chloride, methyl bromide and methyl iodide, the order of boiling points is:Among 1-bromobutane, 2-bromobutane, and 2-bromo-2-methylpropane (isomers, same MW), the boiling point order isIn an SN2 reaction (e.g., CH₃Br + OH⁻):In an SN1 reaction (e.g., tert-butyl bromide + OH⁻):Why is the carbocation formed in SN1 reactions racemised when starting from an optically active substrate?Allylic and benzylic halides react readily by SN1 because:Zaitsev's (Saytzeff's) rule states that in a dehydrohalogenation reaction:In an alkyl halide, the carbon attached to the halogen is called α-carbon and the adjacent carbon is the β-carGrignard reagent (RMgX) is prepared by:Why must Grignard reagents be prepared and handled in scrupulously dry conditions?The Wurtz reaction is best described as:Haloarenes (e.g., chlorobenzene) are much less reactive than haloalkanes toward nucleophilic substitution becaThe C-Cl bond length in chlorobenzene is **shorter** (169 pm) than in methyl chloride (177 pm) because:The presence of an electron-withdrawing group like -NO₂ at the **ortho** or **para** position of haloarene:In electrophilic substitution reactions of haloarenes (e.g., chlorination of chlorobenzene), the halogen substNitration of chlorobenzene gives predominantly:A molecule that is non-superimposable on its mirror image is called:Stereoisomers that are non-superimposable mirror images of each other are called:A racemic mixture is:Among CH₃Cl, CH₃Br, CH₃I, the order of dipole moments is approximately:Why does the reaction of haloalkanes with KCN give predominantly an alkyl cyanide (R-CN), but with AgCN gives Per NCERT §9.2, the general formula of an alkane (saturated open-chain hydrocarbon) is which?Per NCERT §9.2 + Fig 9.1, the H-C-H bond angle in methane and the carbon hybridisation are which?Per NCERT §9.2.2(2)(ii), the Wurtz reaction uses which reagent + solvent for coupling alkyl halides?Per NCERT §9.2.2(3)(i), heating CH₃COONa with NaOH + CaO (soda-lime) produces which gas?Per NCERT §9.2.2(3)(ii), in Kolbe electrolytic synthesis of alkanes, the alkane gas is liberated at which elecPer NCERT §9.2.3, the rate of HALOGENATION of alkanes (F₂, Cl₂, Br₂, I₂) decreases in which order?Per NCERT §9.2.3, the rate of substitution of HYDROGENS in alkane halogenation goes in which order (by carbon Per NCERT §9.2.3 Mechanism, the FIRST step of methane chlorination under sunlight is best described as which?Per NCERT §9.2.4, the STAGGERED conformation of ethane is more stable than the eclipsed conformation by approxPer NCERT §9.2.4, the STAGGERED form of ethane is more stable than ECLIPSED for which reason?Per NCERT §9.2.3 + Table 9.2, isomeric pentanes (n-pentane, 2-methylbutane, neopentane) have which boiling-poiPer NCERT §9.2.2(1), hydrogenation of an alkene to an alkane uses dihydrogen with which kind of catalyst?Per NCERT §9.3.1, in ethene the C-C bond consists of which σ/π combination, and the carbons are which hybridisPer NCERT §9.3.3, geometrical (cis-trans) isomerism in alkenes arises because of which feature of the double bPer NCERT §9.3.3, the dipole moment of cis-but-2-ene (0.33 D) and trans-but-2-ene (≈ 0 D) shows which form is Per NCERT §9.3.4(1), partial reduction of an alkyne to a CIS alkene uses which catalyst?Per NCERT §9.3.4(1), reduction of an internal alkyne with Na in LIQUID NH₃ gives which kind of alkene?Per NCERT §9.3.6 (Markovnikov rule, 1869), HBr addition to propene gives mainly which product?Per NCERT §9.3.6, the peroxide (Kharasch) effect on HBr addition to propene gives mainly which product?Per NCERT §9.3.6, the peroxide effect is observed only with which hydrogen halide?Per NCERT §9.3.6 (electrophilic addition mechanism), the rate-determining intermediate in HBr + propene additiPer NCERT §9.3.6, mild oxidation of an alkene with cold dilute KMnO₄ (Baeyer's reagent) gives which product?Per NCERT §9.3.6 (ozonolysis), reductive ozonolysis of an alkene with O₃ followed by Zn/H₂O gives which class Per NCERT §9.3.6, addition of conc. H₂SO₄ to an alkene followed by water gives mainly which class of compound?Per NCERT §9.4 (structure), the carbon-carbon triple bond in ethyne (HC≡CH) consists of which σ/π combination?Per NCERT §9.4.1, the C-H bond in ethyne is unusually ACIDIC because of which factor?Per NCERT §9.4.2, calcium carbide (CaC₂) reacts with water to give which gas?Per NCERT §9.4.2, dehalogenation of vicinal dihalide with alcoholic KOH gives which class of compound?Per NCERT §9.4.3 (acidic character), terminal alkynes react with sodium metal to liberate which gas + sodium aPer NCERT §9.4.3, addition of water to ethyne in dilute H₂SO₄ with HgSO₄ catalyst gives which final product?Per NCERT §9.4.3, addition of water to propyne under HgSO₄/H₂SO₄ gives mainly which product (Markovnikov)?Per NCERT §9.4.4 (cyclic polymerisation), three molecules of ethyne polymerise over a hot red-hot tube to givePer NCERT §9.4.3 (addition of HBr), HBr addition to propyne gives which Markovnikov product?Per NCERT §9.3.4(1), reduction of an alkyne to a TRANS alkene uses which reagent system?Per NCERT §9.4 (general formula), the general molecular formula of an open-chain alkyne is which?Per NCERT §9.4 (structure), the C-H bond in ethyne has shorter bond length than that in ethane because of whicPer NCERT §9.5.3, the THREE criteria for aromaticity (Hückel) are which set?Per NCERT §9.5.3, for benzene the value of n in Hückel's (4n+2) π electron formula is which?Per NCERT §9.5.2, all six C-C bond lengths in benzene are equal to approximately which value?Per NCERT §9.5.2, the carbon atoms of benzene are which hybridisation?Per NCERT §9.5.5, the FIVE common electrophilic substitution reactions of benzene are which set?Per NCERT §9.5.5 nitration, the actual ELECTROPHILE that attacks benzene in HNO₃ + H₂SO₄ mixture is which specPer NCERT §9.5.5 halogenation, the role of anhydrous AlCl₃ (or FeCl₃) in benzene chlorination is which?Per NCERT §9.5.5(iv), Friedel-Crafts ALKYLATION of benzene uses which reagent system?Per NCERT §9.5.5(v), Friedel-Crafts ACYLATION of benzene uses an acyl halide + AlCl₃ to generate which electroPer NCERT §9.5.5 (EAS mechanism), the carbocation intermediate formed during EAS on benzene is called which spPer NCERT §9.5.6, which of the following groups is a META-directing substituent on benzene?Per NCERT §9.5.6, halogens (-Cl, -Br) on benzene are which kind of directors despite their deactivating -I effThe general formula for alkanes is:Adding HBr to propene CH$_3$-CH=CH$_2$ in absence of peroxide gives mainly:Benzene satisfies Hückel's rule with $4n + 2$ pi electrons for $n =$:Nitration of toluene (methylbenzene) on the lab gives products mostly at:Primary alkyl halides typically undergo nucleophilic substitution by:A tertiary alkyl halide like t-butyl bromide in aqueous ethanol on the bench gives a racemic mixture because:Heating 2-bromobutane with alcoholic KOH on the lab bench primarily gives:Chlorobenzene is much less reactive than chloroethane toward nucleophilic substitution because:Haloalkanes are compounds derived from alkanes by$\mathrm{(CH_3)_3CCl}$ is classified as aWhich haloalkane is MOST reactive toward $\mathrm{S_N 2}$ substitution (with a typical nucleophile like $\mathThe reactivity order for the $\mathrm{S_N 1}$ mechanism among haloalkanes isThe WURTZ REACTION couples two alkyl halides with sodium metal in dry ether to giveFINKELSTEIN REACTION uses NaI (sodium iodide) in dry ACETONE to convert alkyl chlorides into alkyl iodides. ThThe reactivity of haloalkanes toward nucleophilic substitution generally follows the orderA SN2 reaction on a chiral carbon (with a single stereocentre) results inThe IUPAC name of $\mathrm{(CH_3)_2CH{-}CH_2Br}$ isA GRIGNARD REAGENT is formed by reacting an alkyl halide withWhen 1-bromopropane is heated with concentrated alcoholic KOH, the major product isSAYTZEFF'S RULE for elimination reactions states thatChlorobenzene ($\mathrm{C_6H_5Cl}$) is MUCH LESS reactive toward nucleophilic substitution than chloroethane. $\mathrm{CHCl_3}$ (chloroform) on prolonged storage in the air may be partially oxidised to a HIGHLY POISONOUS