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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 651. |
Free radical halogenation takes place in the presence of light or at high temperature (abov 773K.) Formation of halogen free radical intermediate takes place in first step called chain initiation step. `CI_(2)overset(hv)(to)2CI` This reaction is mainly given by those compound which have atleast one hydrogen atom present at `sp^(3)-`hybrid carbon. Reactivity of `sp^(3)-`hybrid carbon depends on the reactivity of reaction intermediate. The relative rate of formation of alkyl radicals by a chlorine radical is : `underset((5))("Tertiary") gt underset((3.8))("Secondary") gt underset((1))("Primary")` `" Percentage yield of the prodcut "=("Relative amount"xx100)/("Sum of relative amounts")` Relative amount = Number of hydrogen atoms on the respective carbon `xx` relative reactivity. NBS (N-bromo succinimide) is used for bromination at allylic and benzylic carbon, whereas `Br_(2)//hv` gives bromination at benzylic allylic and alkyl carbon. which one of the following compounds will react with NBS?A. `CH_(3)-overset(CH_(3))overset(|)underset(CH_(3))underset(|)C-CH=CH_(2)`B. `C_(6)H_(5)-overset(CH_(3))overset(|)underset(CH_(3))underset(|)C-CH_(3)-CH_(3)`C. `C_(6)H_(5)-CH_(2)-CH=CH_(2)`D. `CH_(3)-underset(CH_(3))underset(|)(CH)-CH_(3)` |
| Answer» Correct Answer - C | |
| 652. |
Free radical halogenation takes place in the presence of light or at high temperature (abov 773K.) Formation of halogen free radical intermediate takes place in first step called chain initiation step. `CI_(2)overset(hv)(to)2CI` This reaction is mainly given by those compound which have atleast one hydrogen atom present at `sp^(3)-`hybrid carbon. Reactivity of `sp^(3)-`hybrid carbon depends on the reactivity of reaction intermediate. The relative rate of formation of alkyl radicals by a chlorine radical is : `underset((5))("Tertiary") gt underset((3.8))("Secondary") gt underset((1))("Primary")` `" Percentage yield of the prodcut "=("Relative amount"xx100)/("Sum of relative amounts")` Relative amount = Number of hydrogen atoms on the respective carbon `xx` relative reactivity. NBS (N-bromo succinimide) is used for bromination at allylic and benzylic carbon, whereas `Br_(2)//hv` gives bromination at benzylic allylic and alkyl carbon. `CH_(3)CH_(2)CH_(2)CH_(3)+CI_(2)overset(hv)underset("Light")(to)` `underset("2-Chlorobutane")(CH_(3)overset(O)overset(|)CHCH_(2)CH_(3))+underset("1-Chlorobutane")(CH_(3)CH_(2)CH_(2)CI)` Percentage yield of 2-chlorobutane will be:A. `(15)/(21)xx100`B. `(21)/(21)xx100`C. `(6)/(21)xx100`D. `(3)/(21)xx100` |
| Answer» Correct Answer - A | |
| 653. |
Match the following |
| Answer» Correct Answer - A::B::C::D | |
| 654. |
The necessary condition for halogenation areA. low temperatureB. darknessC. the presence of halogen carrierD. all of these |
| Answer» Correct Answer - C | |
| 655. |
Match Column-I reaction condition with Column -II mechanistic path for the formation of major product |
| Answer» Correct Answer - A::B::C::D | |
| 656. |
how will you prepare 1-bromopropane from propene? |
| Answer» In the presence of organic peroxide. | |
| 657. |
Out of `PCl_(5)` and `SOCl_(2)` which is preferred for preparing chloroalkanes from alcohols? |
| Answer» Correct Answer - `SOCl_(2)` | |
| 658. |
In both alkyl halides and aryl halides, the halogen (X) atom is attached directly to the carbon atom. They are expected to exhibit similar reactivity. However, aryl halides are comparatively very little reactive, particularly towards nucleophilic substitution reaction. for example, hydrolysis of ethyl chloride occurs by simply boiling with aqueous KOH. ON the other hand, the alkaline hydrolysis of chlorobenzene requires a very high temperature (623K) as well as a very high pressure. Q. Among the following which has weakest C-X bond?A. Benzyl bromideB. BromobenzeneC. Vinyl bromideD. Benzyl chloride. |
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Answer» Correct Answer - A `C_(6)H_(5)CH_(2)-Br` has weakest `C-Br` bond because `C_(6)H_(5)overset(o+)(C)H_(2)` ion can be easily resonance stabilised. Moreover, `C-Br` can cleave most readily. |
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| 659. |
Assertion: Aryl halides cannot be prepared by replacement of hydroxyl group of phenol by halogen atom. Reason: Phenols react with halogen acids violently.A. If both assertion and reason are true and reason Is the correct explanation of assertion.B. If both assertion and reason are true but reason is not the correct explanation of assertion.C. If assetion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - C Aryl halides cannot be prepared by replacing hydroxyl group of phenols because the carbon oxygen bond in phenols has a partial double bond character and is difficult to break being stronger than a single bond. |
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| 660. |
If mirror image of the compouns is not superimposable on it, most appropriately it representA. pair of optical active isomersB. pair of structural isomersC. pair of geometrical isomersD. pair of keto-enol tautomers |
| Answer» Correct Answer - A | |
| 661. |
Which among the following has highest B.P. ?A. B. C. D. |
| Answer» Correct Answer - B | |
| 662. |
An alkyl halide by the formation of its grignards reagent and heating with water gives butane. What is the original alkyl halide ?A. Methyl iodideB. n-butyl iodideC. Iso-butyl iodideD. Iso-propyl iodide |
| Answer» Correct Answer - B | |
| 663. |
Consider the following reaction and identify X and Y. `{:(CH_3CH_2CH_2Ioverset(alc.KOH)rarrXoverset(Br_2)rarrY),(" "X" "Y):}`A. `CH_2CH=CH_2 " "CH_3-underset(Br)underset(|)CH-CH_3`B. `CH_3-underset(OH)underset(|)CH-CH_3 " " CH_3-underset(Br)underset(|)CH-CH_3`C. `CH_3CH=CH_2 " "CH_3CH=CH_2" "CH_3CH_2CH_2Br`D. |
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Answer» Correct Answer - A `CH_3CH_2CH_2Ioverset(KOH(alc.))to CH_3-underset((X))(CH)=CH_2` `CH_3underset((X))=CH_2overset(2)toCH_3-underset((Y))underset(Br)underset(|)(CH)-CH_2Br` |
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| 664. |
In which of the following pairs, the bromination of first member is easier than the second member ?A. IsobutaneB. n-Butane isobutaneC. Methane, ethaneD. None of these |
| Answer» Correct Answer - A | |
| 665. |
The number of monochloro product obtained during the reaction of 2,3-dimethyl butane with `CI_(2)` in presence of sunlight is : (do not consider optical isomers)A. 2B. 3C. 4D. 5 |
| Answer» Correct Answer - A | |
| 666. |
The number of monochloro product obtained during the reaction of 2,3-dimethyl butane with `Cl_(2)` in presence of sunlight is : (do not consider optical isomers)A. 2B. 3C. 4D. 5 |
| Answer» Correct Answer - A | |
| 667. |
In the reaction `C_(2)H_(5)-X+KCN overset (alc) to A overset(dil. HCl) to B` The product B isA. `C__(2)H_(5)-CH_(2)NH_(2)`B. `C_(2)H_(5)-Cl`C. `C_(2)H_(5)COOH`D. `C_(2)H_(5)CHO` |
| Answer» Correct Answer - C | |
| 668. |
The reaction is obtained by the action of alcholic KCN and what ?A. 1-butyl ehtyl etherB. 2-methyl 1-propeneC. 2-2-dimethyl butaneD. isopropyl n-propyl ether |
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Answer» Correct Answer - B Sodium ethoxide is a strong base. The nucleophile `C_(2)H_(5)O^()` can not attack at the carbon of C-Cl due to steric hindrance. Hence, elimination reaction occurs to fomr alkene. `CH_(3)- underset(CH_(3)) underset(|)overset(CH_(3)) overset(|)C-Cl+ underset("alc")(C_()H_(5)ONa)+ CH_(3)- overset(CH_(2)) overset(||)C-CH_(3)+C_(2)H_(5)OH+NaCl` |
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| 669. |
Which alkyl halide exhibits complete racemisation in `S_(N^1)` reaction?A. `(CH_3)_2CHCl`B. `CH_3CH_2CH_2CH_2Cl`C. `CH_3CH_2Cl`D. `C_6H_5CH_2Cl` |
| Answer» Correct Answer - D | |
| 670. |
Out of `S_(N^(1))` and `S_(N^(2))` which reaction occurs with (a) inversion of configuration (b) racemisation. |
| Answer» Correct Answer - a,b | |
| 671. |
Out of `S_(N^(1)) and S_(N^(2))` reaction, which is accompanied by inversion of configuration? |
| Answer» `S_(N^(2))` reaction is accompanied by inversion of configuration. | |
| 672. |
The organochlorocompound which shows complete steriochemical inversion during the `S_(N^(2))` reaction is:A. `CH_(3)Cl`B. `C_(2)H_(5)Cl`C. `(CH_(3))_(3)C Cl`D. `(CH_(3))_(2)CHCl` |
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Answer» Correct Answer - A `CH_(3)Cl` (primary alkyl chloride) shows maximum stereochemical inversion because of the least crowding by only alkyl `(CH_(3))` group. |
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| 673. |
What happen when n-butylchloride is treated with alc. KOH. |
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Answer» n-Butylchloride + treated with alc. KOH undergo dehydro dehydro halogenation and forms 1-Butene . `CH_(3) - CH_(2) - CH_(2) - CH_(2) - Cl + "alc." KOH to CH_(3) - CH_(2) - CH = CH_(2) + kCl + H_(2)O` |
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| 674. |
How can you obtain iodoethane from ethanol when no other iodine containing reagent except NAI is available in the laboratery? |
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Answer» NaI does not react directly with ethanol. In order to solve the problem, ethanol is first converted into chloroethane by reacting with HCl (g) in the presence of anhy. `ZnCl_(2)` this is then reacted with NaI in the presence of acetone to form iodoethane by halogen exchange reaction. `underset("Ethanol")(C_(2)H_(5)OH)+HCl(g)overset(ZnCl_(2)("anhyd"))toC_(2)H_(5)Clunderset(("Acetone"))overset("NaI")tounderset("Iodoethane")(C_(2)H_(5)I`. |
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| 675. |
Elimination reaction (especially `beta` - elimination) are as common as the nucleophilic substitution reaction in case of alkyl halides. Specify the reagents used in both cases. |
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Answer» Nucleophilic substitution: By aqueous KOH. Nucleophilic elimination: By alcoholic KOH. |
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| 676. |
Common name of DDT isA. p,p dichloro diphenyl tetrachlorethaneB. p,p-dichlorodiphenyl trichloro ethaneC. p,p- dichlorodipheynl tetrachloro methaneD. p,p-dichlorodiphenyl trichloro methanae |
| Answer» Correct Answer - B | |
| 677. |
the chemcial name of DDT is :A. 2,2-Bis (4-chlorophenyl) trichloropropaneB. 2,2,2-tris (4-chlorophenyl) trichloro ethaneC. 2,2,-Bis (3-chlorophenyl) trichloropropaneD. 2,2,2-tris (3-chlorophenyl) trichloropropane |
| Answer» Correct Answer - A | |
| 678. |
The chemcial formula of test gas is :A. `COCI_(2)`B. `CO_(2)`C. `CI_(2)`D. `C CI_(3)NO_(2)` |
| Answer» Correct Answer - D | |
| 679. |
Aryl halides are less reactive than alkyl halide in mucleophilic substitution reaction which is due to The formation of less stable coarboniumion 2. Reasonance stabilization 3. Longer C-X bond 4. the indicutive effect 5. `sp^(2)`- hybdrizied carbon atom attached to halogenA. 1,3,5B. 2,4,5C. 2,3,5D. 1,2,5 |
| Answer» Correct Answer - D | |
| 680. |
Aryl halids are less reactive rtowards nucleophilic substitution reactions than alkyl halides due to :A. formation of less stable carbocationB. resonance stabilisationC. longer carbon-halogen bondD. `sp^(2)` hybridised carbon attached to halogen. |
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Answer» Correct Answer - B::D both are correct answer. |
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| 681. |
Assertion: Aryl halides are highly reactive towards nucleophilic substitution reactions. Reason: In case of halorenes, halogen atom is attached to sp hybridised carbon atom.A. If both assertion and reason are true and reason Is the correct explanation of assertion.B. If both assertion and reason are true but reason is not the correct explanation of assertion.C. If assetion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - D Aryl halides are less reactive towards nucleophilic substitution reactions as C-X bond aquires a partial double bond character due to resonance. Also halogen atom is attached to `sq^2` hybridised carbon atom. |
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| 682. |
Aryl halides do not undergo nucleophilic substitution reactions under ordinary conditions because: (1). Approach of nucleophile is retarded (2). Carbon carrying halogen atom is `sp^(3)` hybridised. (3). The substrate molecule is destabilised due to resonance (4). of partial double bond character between carbon and halogen.A. 2 and 3 onlyB. 1 and 4 onlyC. 2 and 3 onlyD. 2,3 and 4 only. |
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Answer» Correct Answer - B Both these explanation are correct. |
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| 683. |
Arrange the following compounds in correct decreasing order of reactivity towards `S_(N^(2))` displacement reactions: (i). 1-Bromo-2-methylbutane (ii). 1-Bromo-2,2-dimethylpropane (iii). 1-bromo- methylbutane (iv). 1-Bromobutne |
| Answer» (iv)gt(iii)gt(i)gt(ii) | |
| 684. |
Grignard reagent adds to :A. B. `-C-=N`C. D. All of these |
| Answer» Correct Answer - D | |
| 685. |
The order of reactivities of methyl halide in the formation of Grignard reagent isA. `CH_3IgtCH_3BrgtCH_3Cl`B. `CH_3ClgtCH_3BrgtCH_3I`C. `CH_3BrgtCH_3ClgtCH_3I`D. `CH_3BrgtCH_3IgtCH_3Cl` |
| Answer» Correct Answer - A | |
| 686. |
PhMgBr (Grignard reagent ) cannot be used to prepare the compound ?A. B. C. D. |
| Answer» Correct Answer - 4 | |
| 687. |
Why is it necessary to avoid even traces of moisture during the use of a Grignard reagent? |
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Answer» Grignard reagent `(RMgX)` is highly reactive. Even in the presence of traces of water it gets hydrolysed to form a hydrocarbon (alkane). It is therefore, synthesised as well as used in completely anhydrous conditions. Normally completely anhydrous ether is used for this purpose `R-MgX+H_(2)Otounderset("Alkane")(R-H)" "+underset("Basic mag. halide")(Mg(OH)X)` |
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| 688. |
Which of the following alkyl halide is hydrolysed by `S_(N^(1))` meachanism ?A. `(CH_(3))_(2) CHX`B. `(CH_(3)CH_(2)X`C. `CH_(3)CH_(2)CH_(2)X`D. `(CH_(3))_(3)CX` |
| Answer» Correct Answer - D | |
| 689. |
the incorrect statement with respect to `S_(N^(1) " and " S_(N^(2))` mechanisms for alkyl halide is :A. a strong nucleophilic in an aprotic solvent increases the rate or favours `S_(N^(2))` reactionB. a weak nucleophilic and a protic solvent inceases the rate or favours `S_(N^(1))` reactionC. competing reaction for an `S_(N^(2))` reaction rearrangementD. `S_(N^(1))` reaction can be cataylsed by some Lewis acids |
| Answer» Correct Answer - C | |
| 690. |
Which of the following statement regarding `S_(N)1` reaction shown by alkyl halide is incorrect?A. The added nucleophile plays no kinetic role in `S_(N^1)` reaction.B. The `S_(N^1)` reaction involves the inversion of configuration of the optically active substrate.C. The `S_(N^1)` reaction on the chiral starting material ends up with race mistration of the product.D. The more stable the carbocation intermediate the faster the `S_(N^1)` reaction. |
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Answer» Correct Answer - B In `S_(N^1)` reaction, rate of substitution depends on the concentration of substrate. In case of `S_(N^1)`reaction there si racemisation. `S_(N^1)` reaction will be faster, if carbocation formed is more stable. |
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| 691. |
Which of the following is halogen exchange reaction ?A. `RX+Nal to Rl+NaX`B. C. `R-OH+Hxoverset(ZnCl_(2))toR-X+H_(2)O`D. |
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Answer» Correct Answer - A Halogen exchange reactions are those reactions in which one halide replaces another in option (a) halogen (-X) is replaced by iodine. This reaction is named as Finkelstein reaction. In option (b),there is the addition of hydrogen hailde on alkene. In option (c) ,halogen replaces alcoholic group. While in option (d) halogen replaces the hydrogen of benzene ring. |
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| 692. |
The major product is formed when toluene si reacted with chlorine in the presence of halogen carrier.A. B. C. D. |
| Answer» Correct Answer - B | |
| 693. |
The arrangement of following compounds: (I) bromomethane (II). Bromoform (III). Chloromethane (IV). Dibromomethane. In increasing order of boiling points isA. `(IV) lt (III) lt (I)lt(II)`B. `(I)lt(II)lt(III)lt(IV)`C. `(III)lt(I)lt(IV)lt(II)`D. `(II)lt(I)lt(IV)lt(II)` |
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Answer» Correct Answer - C The magnitude of the boiling point depends upon the size of the halogen atom and also the number of halogen atoms present. Keeping this veiw, it is the correct increasing order boiling point. |
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| 694. |
Toluene react with a halogen in the presence of iron (III) chloride giving ortho andpara halo compounds. The reactions isA. Electrophilic elimination reaction.B. Electrophilic substitution reactionC. Free radical addition reactionD. Nucleophilic substitution reaction. |
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Answer» Correct Answer - B The reaction is known as electrophilic substitution reaction. |
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| 695. |
Which of the following is an example of vic-dihalide?A. Dichloromethane.B. 1,2-dichloroethaneC. Ethylidene chloride.D. Allyl chloride. |
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Answer» Correct Answer - B It is a vic (1,2), dihalide i.e., It is attached to the carbon atom next to the double bond. |
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| 696. |
Which reagent will you use for the following reaction ? `CH_(3)CH_(2)CH_(2)CH_(3)toCH_(3)CH_(2)CH_(2)CH_(2)Cl+CH_(3)CH_(2)CHClCH_(3)`A. `Cl_(2)//UV` lightB. `NaCl+H_(2)SO_(4)`C. `Cl_(2)` has in the darkD. `Cl_(2)` gas in the presence of iron in dark. |
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Answer» Correct Answer - A it is a photochemical reaction. |
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| 697. |
Which of the following is halogen exchange reaction ?A. `RX+NaltoRI+NaX`C. `R-OH+Hxoverset(ZnCl_(2))toR-X+H_(2)O` |
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Answer» Correct Answer - A It is the correct answer. It is an example of finkelstein reaction |
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| 698. |
Assertion: p-dichloroebenzene is less soluble in organic solvents than the corresponding o-isomer. Reason: o-dichlorobenzene is polar while p-dichlorobenzene is not.A. If both assertion and reason are correct and reason is correct explanation for assertionB. If both assertion and reason are correct but reason is not correct explanation for assertion.C. If assertion is correct but reason is incorrect.D. if both assertion and reason are incorrect. |
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Answer» Correct Answer - B Correct explanation. The structure of p-dichlorobenzene is more symmetrical than that of ortho isomer. Being a solid, its crystal lattice is more stable and therefore greater energy is needed to break the lattice. Therefore it is less soluble. |
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| 699. |
p-Dichlorobenzene has higher m.p. than those of o- and m-isomers. Discuss |
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Answer» The p-isomer being more symmetrical fits closely in the crystal lattice and thus has stronger inter- molecular forces of attraction than o- and m-isomers. Since during melting or dissolution, the crystal lattice breaks, therefore, a large amount of energy is needed to melt or dissolve the p-isomer than the corresponding o-and m-isomers. ln other words, the melting point of the p-isomer is higher and its solubility lower than the corresponding o-and m-isomers. |
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| 700. |
Assertion: Molecules that are not superimposable on their mirror images are chiral. Reason: All chiral molecules hae chiral centres.A. If both assertion and reason are correct and reason is correct explanation for assertionB. If both assertion and reason are correct but reason is not correct explanation for assertion.C. If assertion is correct but reason is incorrect.D. if both assertion and reason are incorrect. |
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Answer» Correct Answer - C Correct reason. Chiral molecules are dissymmetric in nature. |
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