123 + Interview Questions in Haloalkanes And Haloarenes in Chemistry

1.	Which of the following has a chiral carbon atom?(a) 2-Chloro-2-methylpentane(b) 1,1-Dibromoethane(c) Pentan-3-ol(d) 2-BromopentaneI had been asked this question in semester exam.The doubt is from Haloalkanes & Haloarenes in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» RIGHT ANSWER is (d) 2-Bromopentane The best I can explain: A CHIRAL carbon atom is that which has four different substituent groups attached to it. 2-Bromopentane has one of each H, CH3, C3H7 and Br groups attached to its C atom.

Discussion

2.	The rate of the following reaction depends on the concentration of which reactant(s)/?(a) tert-Butyl bromide(b) Hydroxide ion(c) Both tert-Butyl bromide and hydroxide ion(d) None of the reactantsThe question was asked in an online interview.My doubt is from Haloalkanes & Haloarenes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» CORRECT choice is (a) tert-Butyl bromide To explain: This is an example of a SN1 reaction, where the rate depends on the concentration of only the ALKYL halide, because that will DETERMINE the concentration of carbocation FORMED in the FIRST step.

Discussion

3.	What is the correct relation between boiling points of the following alkyl iodides, where R=methyl, R’=ethyl and R”=propyl?(a) RI > R’I > R”I(b) R”I > R’I > RI(c) RI = R’I = R”I(d) R”I = R’I > RII have been asked this question in homework.This intriguing question originated from Haloarenes Physical Properties in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct answer is (b) R”I > R’I > RI Easiest explanation: The FORCES of attraction BECOME STRONGER as the molecules getter bigger in SIZE and number of electrons increases. Hence, the methyl halides will have the lowest boiling points among all ALKYL groups.

Discussion

4.	Which of the following is a reagent used in the preparation of benzene diazonium chloride from aniline?(a) Sodium hydroxide(b) Sodium chloride(c) Sodium nitrite(d) Sodium nitrateThis question was posed to me in examination.This is a very interesting question from Preparation of Haloarenes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct option is (c) Sodium nitrite For EXPLANATION: Sodium nitrite reacts with aqueous HCl to form NaCl and HNO2. The nitrous acid reacts with aniline in cold aqueous solution of HCl to form benzene DIAZONIUM CHLORIDE.

Discussion

5.	The ortho and para isomers formed by electrophilic substitution of arenes can be easily separated due to the large difference in their ________(a) densities(b) solubilities(c) melting points(d) boiling pointsThis question was addressed to me by my school principal while I was bunking the class.Query is from Preparation of Haloarenes in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right choice is (c) melting points To elaborate: The solid form of ortho isomer MELTS WAY earlier than the para isomer as the latter has a HIGHER melting POINT due to its symmetric GEOMETRY.

Discussion

6.	The size of the halogen atom _________ as we go down the group in the periodic table.(a) increases(b) decreases(c) remains same(d) increases then decreasesI got this question by my college professor while I was bunking the class.My question is taken from Nature of C-X Bond topic in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The CORRECT answer is (a) INCREASES For EXPLANATION I would say: The common trend within the halogen group in the periodic table is that the size of the ATOM increases from top to BOTTOM.

Discussion

7.	Identify the correct naming of the compound H3C-CHCl2 from the following?(a) Ethylidene chloride(b) Ethylene dichloride(c) 1,2-Dichloroethane(d) Vic-dichlorideThis question was addressed to me in homework.My doubt is from Haloalkanes Nomenclature in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The CORRECT answer is (a) Ethylidene chloride The BEST I can explain: The GIVEN compound is a dihaloalkane with both the halogens on the same carbon atom. These are ALSO known as gem-dihalides or ALKYLIDENE halides.

Discussion

8.	Which of the following polyhalogen compounds in useful in extinguishing fires?(a) Dichloromethane(b) Trichloromethane(c) Triiodomethane(d) TetrachloromethaneI had been asked this question in examination.Question is from Haloalkanes & Haloarenes in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right choice is (d) Tetrachloromethane The explanation: CARBON tetrachloride is used as a CLEANING fluid, degreasing AGENT, spot remover and a fire EXTINGUISHER.

Discussion

9.	Identify the catalyst in Friedel-Crafts acylation reaction.(a) Anhydrous FeCl3(b) Anhydrous AlCl3(c) NaNO2(d) Alcoholic KOHI had been asked this question in a national level competition.The question is from Haloalkanes & Haloarenes in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct choice is (B) ANHYDROUS AlCl3 Explanation: Friedel-Crafts acylation is carried out by treating a HALOARENE with and ACETYL chloride in the presence of anhydrous aluminium chloride as a catalyst.

Discussion

10.	The dipole moment of chloromethane is higher than that of fluoromethane.(a) True(b) FalseI got this question in class test.This question is from Haloarenes Physical Properties in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right choice is (a) True To elaborate: Although the F atom is much more electronegative than Cl, the very SMALL SIZE of F COMPARED to Cl results in the product of CHARGE and distance, i.e., DIPOLE moment, of CH3F to be lower than that of CH3Cl.

Discussion

11.	Identify the nucleophile in the substitution reaction between water and bromopropane.(a) Br^–(b) H^+(c) OH^–(d) H2OThis question was addressed to me during an interview.The origin of the question is Haloalkanes & Haloarenes in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct answer is (d) H2O The explanation: The WATER MOLECULE itself is the nucleophile which has two PAIRS on electrons on the O atom and ATTACKS the Br atom in the haloalkane.

Discussion

12.	How many isomers does C5H11Br have?(a) 4(b) 6(c) 8(d) 10I had been asked this question during an interview for a job.My question is taken from Haloalkanes Nomenclature in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right option is (C) 8 The EXPLANATION is: It has a total of 8 ISOMERS, four are primary and two each are secondary and TERTIARY HALOALKANES.

Discussion

13.	Which of the following is an effect of exposure to low levels of dichloromethane in the air?(a) Slightly impaired vision(b) Dizziness(c) Nausea(d) Numbness in fingersThe question was posed to me in a national level competition.My doubt is from Haloalkanes & Haloarenes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct option is (a) Slightly IMPAIRED vision Best explanation: DIZZINESS, nausea and numbness are caused due to HIGHER levels of dichloromethane in the air. Lower levels cause SLIGHT impairment of hearing and vision.

Discussion

14.	Predict the minor product formed when chlorobenzene reacts with chloromethane in the presence of anhydrous AlCl3?(a) Toluene(b) m-Chlorotoluene(c) o-Chlorotoluene(d) p-ChlorotolueneI got this question in homework.I need to ask this question from Haloalkanes & Haloarenes in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right answer is (c) o-Chlorotoluene The best explanation: This is the Friedel-Crafts ALKYLATION REACTION, where o-Chlorotoluene is the minor product and p-Chlorotoluene is the MAJOR product. This is because HALOGEN group is ortho and para DIRECTING.

Discussion

15.	How many β-carbon atoms does 2-Bromobutane have?(a) 0(b) 1(c) 2(d) 3I got this question in my homework.I want to ask this question from Haloalkanes & Haloarenes topic in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct choice is (b) 1 The BEST explanation: A beta carbon is the carbon atom that is adjacent to the carbon atom that is ATTACHED to the halogen. In 2-Bromobutane, the halogen is at position C-2, so the ALPHA carbon has one carbon on either side, making it two beta carbons

Discussion

16.	If the bond length of C-Cl bond in chloromethane is 178pm, what will be the probable bond length of C-Br bond in bromomethane?(a) 139pm(b) 156pm(c) 178pm(d) 193pmThe question was asked during an online interview.This question is from Nature of C-X Bond in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct choice is (d) 193pm For explanation I would SAY: The size of Cl atom is smaller than the size of Br atom as the latter APPEARS LOWER than Cl in the HALOGEN group. Hence, the carbon-halogen bond length of C-Br must be bigger than that of C-Cl, i.e., 178pm, THEREFORE it must be 193pm.

Discussion

17.	What is the IUPAC name for the compound (CH3)3CCH2Cl?(a) 1-Chloro-2,2-dimethylpropane(b) 1-Chloro-2,2,2-trimethylethane(c) 2-Chloromethyl-2-methylpropane(d) 2,2-Dimethly-1-BromopropaneThe question was posed to me by my college professor while I was bunking the class.This intriguing question originated from Haloalkanes Nomenclature in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct option is (a) 1-Chloro-2,2-dimethylpropane To elaborate: There are two different POSSIBLE chains that CONSISTS of maximum 3 C ATOMS. One of them has two methyl and one chloro group and the other has one methyl and one complex SUBSTITUENT. The preference is given to the former with the chloro at C-1 and the 2 methyl groups at C-2.

Discussion

18.	What is the nature of the circled C atom in the following compound?(a) sp^2 hybridised(b) allylic(c) benzylic(d) vinylicThe question was posed to me in an online quiz.My question is from Haloalkanes Classification topic in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» CORRECT answer is (C) benzylic Easiest EXPLANATION: The circled C atom is sp^3 hybridised and is attached directly to an aromatic RING, hence it is a benzylic carbon and the COMPOUND is a 1o benzylic halide.

Discussion

19.	What is the class of the substitution product of the reaction between LiAlH4 and an alkyl halide?(a) Haloalkane(b) Hydrocarbon(c) Nitroalkane(d) Alkyl nitriteThis question was posed to me in exam.My doubt is from Haloalkanes & Haloarenes in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct choice is (b) Hydrocarbon Easiest EXPLANATION: The nucleophile in LiAlH4 is the H ATOM which attacks the halogen in the alkyl HALIDE and substitutes it to form the BASIC hydrocarbon.

Discussion

20.	What will be the class of the nucleophilic substitution product when sodium hydroxide reacts with chloroethane?(a) Alkane(b) Alcohol(c) Amine(d) EtherThe question was posed to me at a job interview.The query is from Haloalkanes & Haloarenes in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» CORRECT choice is (b) Alcohol The BEST I can EXPLAIN: The OH^– nucleophile SUBSTITUTES the Cl^– ION in chloroethane to form ethanol, which is an alcohol.

Discussion

21.	Which of the following has the highest boiling point?(a) Chloromethane(b) Dichloromethane(c) Trichloromethane(d) TetrachloromethaneI have been asked this question in an online interview.I need to ask this question from Haloarenes Physical Properties topic in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct option is (d) Tetrachloromethane Easiest explanation: The boiling POINTS increase with the NUMBER of halogen atoms as the MOLECULAR masses increase and so do the intermolecular forces of ATTRACTION.

Discussion

22.	Which of the following is incorrect with regard to the reaction between C2H4 and Cl2 in CCl4?(a) It results in the formation of a vicinal dihalide(b) It results in the breaking of the C-C double bond(c) It results in the formation of a colourless compound(d) It results in the discharge of a reddish-brown colourThe question was asked in a job interview.Question is from Methods of Preparation of Haloalkanes in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The CORRECT option is (d) It results in the discharge of a reddish-brown colour To elaborate: The reddish-brown colour is discharged when Br2 reacts with an alkene to form a vic-dihalide. This makes it an IMPORTANT test for the detection of a double BOND.

Discussion

23.	The compound in which a CH2Br group is attached to a benzene ring is an aryl halide.(a) True(b) FalseThis question was posed to me in examination.My question is from Haloalkanes Classification topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right choice is (b) False Explanation: The Br atom is BONDED to a carbon atom which is ATTACHED to sp^2 hybridised carbon of benzene. This is an example of a SIDE chain SUBSTITUTED ARYL halide.

Discussion

24.	What is the general formula for haloalkanes? (X=halogen atom, n = 1, 2, 3…)(a) CnH2nX(b) CnH2n+1X(c) CnH2n-1X(d) CnH2n-3XI got this question in an online interview.The question is from Haloalkanes Classification topic in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right choice is (b) CnH2n+1X The explanation: The GENERAL formula for haloalkanes is CnH2n+1X where X is a halogen ATOM and n = 1, 2, 3… The formulae CnH2n-1X and CnH2n-3X are that of haloalkenes and haloalkynes respectively.

Discussion

25.	Monohalo, dihalo, trihalo and tetrahalo are types of haloalkanes and haloarenes based on the ______(a) type of halogen atom(b) number of halogen atoms(c) nature of carbon atom(d) hybridisation of C atom to which halogen is bondedI had been asked this question in an interview for internship.The query is from Haloalkanes Classification topic in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct choice is (b) number of halogen ATOMS The best explanation: Haloalkanes may be classified as MONO, di, TRI, TETRA and so on depending on the number of halogen atoms present in their STRUCTURE.

Discussion

26.	The oxidation of trichloromethane results in the formation of a poisonous gas called ________(a) carbon monoxide(b) carbonyl chloride(c) hydrogen sulphide(d) phosphineThe question was posed to me at a job interview.My question is based upon Haloalkanes & Haloarenes topic in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct option is (b) carbonyl chloride For explanation I would SAY: Trichloromethane is slowly OXIDIZED in air in the presence of light to form an extremely poisonous gas, carbonyl chloride, ALSO called as PHOSGENE.

Discussion

27.	Predict the chirality of the shown compounds.(a) Both A and B are chiral(b) Both A and B are achiral(c) A is chiral and B is achiral(d) A is achiral and B is chiralThe question was posed to me in an interview.I want to ask this question from Haloalkanes & Haloarenes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» CORRECT answer is (c) A is CHIRAL and B is achiral To elaborate: The C ATOM that is attached to the OH group in compound A is a stereocenter and MAKES the compound A chiral. On the other hand, compound B does not have any asymmetric carbon.

Discussion

28.	Which of the following statements in incorrect regarding SN2 mechanisms?(a) The rate of the reaction depends on the concentration of both reactants(b) The complete mechanism takes place in a single step(c) The transition state is stable(d) There is inversion of configurationThis question was addressed to me in an interview for internship.The above asked question is from Haloalkanes & Haloarenes in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct answer is (c) The transition state is stable The best explanation: In the transition state of SN2 mechanisms, the CARBON atoms is simultaneously bonded to the incoming nucleophile and the OUTGOING GROUP and is hence bonded to five atoms at the same TIME. Such a geometry is unstable and cannot be ISOLATED.

Discussion

29.	The SN1 reaction cannot be carried out in which of the following media?(a) Acetic acid(b) Acetone(c) Ethanol(d) WaterI got this question during an internship interview.My question is taken from Haloalkanes & Haloarenes in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» CORRECT option is (b) Acetone The best I can explain: SN1 reactions are carried out in POLAR PROTIC solvents LIKE water, alcohol and acetic acid. These solvents promote the ionisation step by stabilising the IONS by solvation.

Discussion

30.	What is the chirality of 2-Chlorobutane?(a) Chiral(b) Achiral(c) Superimposable mirror images(d) SymmetricThis question was addressed to me in an interview for job.My doubt stems from Haloalkanes & Haloarenes topic in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The CORRECT answer is (a) CHIRAL Best explanation: 2-Chlorobutane has four different groups ATTACHED to the TETRAHEDRAL carbon and is chiral as it forms non-superimposable MIRROR images.

Discussion

31.	Which of the following is not an ambident nucleophile?(a) Hydroxide(b) Thiocyanate(c) Cyanide(d) NitriteI had been asked this question in examination.This intriguing question originated from Haloalkanes & Haloarenes in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right OPTION is (a) Hydroxide The best EXPLANATION: Ambident nucleophiles are those that have two NUCLEOPHILIC CENTRES and can LINK through any of their two atoms to result in the formation of different compounds.

Discussion

32.	Which of the following has the lowest boiling point?(a) Bromomethane(b) Bromoform(c) Chloromethane(d) DibromomethaneThe question was asked in an interview.I'd like to ask this question from Haloarenes Physical Properties topic in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right answer is (c) CHLOROMETHANE Easiest explanation: Since BOILING POINT increases with increases in molecular MASS, chloromethane has the lowest molecular mass and HENCE the lowest boiling point.

Discussion

33.	Which of the following haloalkanes exist as liquids at room temperature?(a) Methyl chloride(b) Methyl bromide(c) Ethyl chloride(d) Propyl bromideThis question was addressed to me by my college director while I was bunking the class.I'm obligated to ask this question of Haloarenes Physical Properties in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct ANSWER is (d) Propyl bromide For explanation: The lower members like methyl chloride, methyl bromide and ethyl chloride EXIST as gases at room TEMPERATURE. The higher members EXISTS as liquids or SOLIDS.

Discussion

34.	In the iodination of benzene, which compound causes the reduction of iodobenzene back to benzene?(a) Iodic acid(b) Hydrogen iodide(c) Nitric acid(d) Mercuric oxideI had been asked this question in a national level competition.My question is from Preparation of Haloarenes in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct choice is (b) Hydrogen iodide For EXPLANATION I would SAY: The hydrogen iodide formed during the IODINATION of benzene is strong reducing agent which reverses the reaction. To prevent this, oxidising agents like HIO4, HNO3 and HgO are USED in the reaction so as to oxidize the HI to IODINE.

Discussion

35.	The Finkelstein reaction takes place in what medium?(a) Concentrated HCl(b) Concentrated H2SO4(c) Dry acetone(d) WaterThe question was asked in an interview for job.Enquiry is from Methods of Preparation of Haloalkanes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct choice is (c) Dry acetone To explain I would say: When the alkyl bromide/chloride reacts with sodium IODIDE in dry acetone, the NABR or NACL formed gets PRECIPITATED in dry acetone. This facilitates the forward REACTION according to Le Chatelier’s Principle.

Discussion

36.	What do you get by heating a mixture of hexanol and concentrated aqueous hydrogen chloride?(a) Cyclochlorohexane(b) Chlorohexane(c) Phosphorus acid(d) No reactionI had been asked this question during an interview.My question comes from Methods of Preparation of Haloalkanes in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right choice is (b) Chlorohexane Best explanation: Alkyl chlorides can be prepared by HEATING a MIXTURE of ALCOHOL and concentrated AQUEOUS HALOGEN acid.

Discussion

37.	Identify the correct common name for CH3CH2CH2CH2Cl.(a) Isobutyl chloride(b) n-Butyl chloride(c) sec-Butyl chloride(d) tert-Butyl chlorideThe question was posed to me in an online quiz.My enquiry is from Haloalkanes Nomenclature topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» CORRECT option is (b) N-Butyl chloride Explanation: The compound shown is 1-Chlorobutane which has 4 C atoms in the parent CHAIN and the only halogen compound present at the end of the chain. This type structure has the PREFIX n- in the common NAME.

Discussion

38.	Which of the following is not a harmful effect of DDT?(a) It is non-biodegradable(b) Cannot be metabolized by animals(c) Highly toxic towards fish(d) Causes air pollutionI got this question by my school teacher while I was bunking the class.My question comes from Haloalkanes & Haloarenes in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The CORRECT option is (d) Causes air pollution To explain: The chemical stability and fat solubility of DDT is a big DRAWBACK. It was banned due to its harmful EFFECT on ANIMALS and fish.

Discussion

39.	Fittig reaction results in the formation of a diphenyl.(a) True(b) FalseI got this question during an online exam.This intriguing question originated from Haloalkanes & Haloarenes in division Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct choice is (a) True The explanation is: Aryl halides GIVE analogous compounds in which two aryl GROUPS are combined when treated with Na in dry ETHER. This is CALLED Fittig reaction.

Discussion

40.	Identify ‘X’ from the reaction shown.(a) Dilute H2SO4(b) Concentrated H2SO4(c) Dilute HNO3(d) Concentrated HNO3This question was addressed to me by my school principal while I was bunking the class.Enquiry is from Haloalkanes & Haloarenes in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Right choice is (b) Concentrated H2SO4 Best explanation: This is the sulphonation of CHLOROBENZENE which RESULTS in the formation of ORTHO and META chlorobenzenesulfonic acid.

Discussion

41.	What is the major product formed when chlorobenzene reacts with nitric acid in concentrated sulphuric acid?(a) Nitrobenzene(b) 1-Chloro-2-nitrobenzene(c) 1-Chloro-3-nitrobenzene(d) 1-Chloro-4-nitrobenzeneThe question was asked in homework.This is a very interesting question from Haloalkanes & Haloarenes topic in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The CORRECT answer is (d) 1-Chloro-4-nitrobenzene For EXPLANATION I would say: This is the NITRATION of chlorobenzene which is an electrophilic substitution reaction. The MAJOR product is that where the nitro group is present at a para POSITION to Cl.

Discussion

42.	What is formed when ethyl magnesium bromide reacts with water?(a) Grignard reagent(b) Ethane(c) Ethanol(d) Magnesium hydroxideThe question was asked during an interview.This key question is from Haloalkanes & Haloarenes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The CORRECT answer is (b) Ethane The best I can explain: Ethyl magnesium bromide is a Grignard reagent and is highly reactive to any proton giving source because of the polar nature of BONDING PRESENT in it. It FORMS hydrocarbons when reacted with water.

Discussion

43.	What is the most suitable term for the following transformation?(a) Inversion of configuration(b) Retention of configuration(c) Racemisation(d) Elimination reactionI have been asked this question in an online quiz.This key question is from Haloalkanes & Haloarenes in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct option is (b) Retention of configuration The BEST I can explain: It can be seen that the relative spatial arrangement of bonds at the stereocenter REMAIN the same even after the transformation. Hence, this transformation is said to take PLACE with a retention of configuration.

Discussion

44.	Which of the following will have the highest reactivity towards SN2 reaction, where R=methyl group?(a) R-F(b) R-Cl(c) R-Br(d) R-II had been asked this question in examination.I want to ask this question from Haloalkanes & Haloarenes in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct CHOICE is (d) R-I The best I can explain: Iodine is a BETTER leaving groups among the halogens as it has a better ABILITY to ACCOMMODATE the negative charge.

Discussion

45.	What is the correct order of boiling of isomeric dichlorobenzenes?(a) ortho>meta>para(b) para>meta>ortho(c) para>ortho>meta(d) meta>ortho>paraI got this question in an internship interview.My query is from Haloarenes Physical Properties in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» CORRECT answer is (c) PARA>ortho>META Explanation: Para isomers have the highest melting points due to their symmetry and ease with which they can fit into a crystal lattice COMPARED to meta and ortho isomers.

Discussion

46.	The reaction of a primary alcohol with which of the following gives purely a haloalkane?(a) Phosphorus trichloride(b) Phosphorus pentachloride(c) Thionyl chloride(d) Sulphuryl chlorideThe question was posed to me by my college professor while I was bunking the class.This key question is from Methods of Preparation of Haloalkanes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The CORRECT OPTION is (c) Thionyl chloride The best I can explain: The reaction of alcohol with SOCl2 gives a chloroalkane ALONG with GASES SO2 and HCl which are easily escapable, LEAVING behind the pure alkyl chloride.

Discussion

47.	What is the correct order of reactivity of the following haloacids with a given alcohol?(a) HCl > HBr > HI(b) HI > HBr > HCl(c) HBr > HCl > HI(d) HI > HCl > HBrI have been asked this question in quiz.My query is from Methods of Preparation of Haloalkanes topic in section Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct answer is (B) HI > HBr > HCl To explain: The bond dissociation enthalpy of the carbon-halogen bond between H and CL is the HIGHEST and that between H and I is the LOWEST among HI, HBr and HCl.

Discussion

48.	The bond length between carbon and fluorine is the largest among all other halogens.(a) True(b) FalseI got this question by my school teacher while I was bunking the class.My doubt stems from Nature of C-X Bond in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» The correct choice is (b) False To explain I would say: Since FLUORINE has the smallest ATOMIC SIZE among the halogens, it will form the smallest carbon-halogen bond in haloalkanes.

Discussion

49.	Which of the following compounds contains an allylic carbon?(a) A(b) B(c) C(d) DThis question was addressed to me in a job interview.Query is from Haloalkanes Classification in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct CHOICE is (a) A For explanation I would say: A sp^3 hybridised C atom present ADJACENT to a C-C DOUBLE BOND is called an allylic carbon, and when the HALOGEN atom is bonded to this carbon, it is called an allylic halide.

Discussion

50.	Compared to haloalkanes, the reactivity of haloarenes towards nucleophilic substitution reactions is _________(a) low(b) high(c) very high(d) equalThis question was posed to me in an internship interview.My doubt stems from Haloalkanes & Haloarenes topic in chapter Haloalkanes and Haloarenes of Chemistry – Class 12
Answer» Correct OPTION is (a) low For explanation I would SAY: Haloarenes form resonating structures in which the carbon-halogen bond acquires a partial double bond character and its cleavage is difficult. Hence, they are less REACTIVE TOWARDS nucleophilic substitution REACTIONS.

Discussion

Explore topic-wise InterviewSolutions in .

Which of the following has a chiral carbon atom?(a) 2-Chloro-2-methylpentane(b) 1,1-Dibromoethane(c) Pentan-3-ol(d) 2-BromopentaneI had been asked this question in semester exam.The doubt is from Haloalkanes & Haloarenes in chapter Haloalkanes and Haloarenes of Chemistry – Class 12

Identify the catalyst in Friedel-Crafts acylation reaction.(a) Anhydrous FeCl3(b) Anhydrous AlCl3(c) NaNO2(d) Alcoholic KOHI had been asked this question in a national level competition.The question is from Haloalkanes & Haloarenes in portion Haloalkanes and Haloarenes of Chemistry – Class 12

The dipole moment of chloromethane is higher than that of fluoromethane.(a) True(b) FalseI got this question in class test.This question is from Haloarenes Physical Properties in division Haloalkanes and Haloarenes of Chemistry – Class 12

Identify the nucleophile in the substitution reaction between water and bromopropane.(a) Br^–(b) H^+(c) OH^–(d) H2OThis question was addressed to me during an interview.The origin of the question is Haloalkanes & Haloarenes in section Haloalkanes and Haloarenes of Chemistry – Class 12

How many isomers does C5H11Br have?(a) 4(b) 6(c) 8(d) 10I had been asked this question during an interview for a job.My question is taken from Haloalkanes Nomenclature in division Haloalkanes and Haloarenes of Chemistry – Class 12

How many β-carbon atoms does 2-Bromobutane have?(a) 0(b) 1(c) 2(d) 3I got this question in my homework.I want to ask this question from Haloalkanes & Haloarenes topic in chapter Haloalkanes and Haloarenes of Chemistry – Class 12

What is the nature of the circled C atom in the following compound?(a) sp^2 hybridised(b) allylic(c) benzylic(d) vinylicThe question was posed to me in an online quiz.My question is from Haloalkanes Classification topic in division Haloalkanes and Haloarenes of Chemistry – Class 12

The compound in which a CH2Br group is attached to a benzene ring is an aryl halide.(a) True(b) FalseThis question was posed to me in examination.My question is from Haloalkanes Classification topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12

What is the general formula for haloalkanes? (X=halogen atom, n = 1, 2, 3…)(a) CnH2nX(b) CnH2n+1X(c) CnH2n-1X(d) CnH2n-3XI got this question in an online interview.The question is from Haloalkanes Classification topic in division Haloalkanes and Haloarenes of Chemistry – Class 12

The SN1 reaction cannot be carried out in which of the following media?(a) Acetic acid(b) Acetone(c) Ethanol(d) WaterI got this question during an internship interview.My question is taken from Haloalkanes & Haloarenes in division Haloalkanes and Haloarenes of Chemistry – Class 12

What is the chirality of 2-Chlorobutane?(a) Chiral(b) Achiral(c) Superimposable mirror images(d) SymmetricThis question was addressed to me in an interview for job.My doubt stems from Haloalkanes & Haloarenes topic in section Haloalkanes and Haloarenes of Chemistry – Class 12

Which of the following is not an ambident nucleophile?(a) Hydroxide(b) Thiocyanate(c) Cyanide(d) NitriteI had been asked this question in examination.This intriguing question originated from Haloalkanes & Haloarenes in section Haloalkanes and Haloarenes of Chemistry – Class 12

Which of the following has the lowest boiling point?(a) Bromomethane(b) Bromoform(c) Chloromethane(d) DibromomethaneThe question was asked in an interview.I'd like to ask this question from Haloarenes Physical Properties topic in division Haloalkanes and Haloarenes of Chemistry – Class 12

The Finkelstein reaction takes place in what medium?(a) Concentrated HCl(b) Concentrated H2SO4(c) Dry acetone(d) WaterThe question was asked in an interview for job.Enquiry is from Methods of Preparation of Haloalkanes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12

Identify the correct common name for CH3CH2CH2CH2Cl.(a) Isobutyl chloride(b) n-Butyl chloride(c) sec-Butyl chloride(d) tert-Butyl chlorideThe question was posed to me in an online quiz.My enquiry is from Haloalkanes Nomenclature topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12

Fittig reaction results in the formation of a diphenyl.(a) True(b) FalseI got this question during an online exam.This intriguing question originated from Haloalkanes & Haloarenes in division Haloalkanes and Haloarenes of Chemistry – Class 12

What is formed when ethyl magnesium bromide reacts with water?(a) Grignard reagent(b) Ethane(c) Ethanol(d) Magnesium hydroxideThe question was asked during an interview.This key question is from Haloalkanes & Haloarenes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12

Which of the following will have the highest reactivity towards SN2 reaction, where R=methyl group?(a) R-F(b) R-Cl(c) R-Br(d) R-II had been asked this question in examination.I want to ask this question from Haloalkanes & Haloarenes in portion Haloalkanes and Haloarenes of Chemistry – Class 12

The bond length between carbon and fluorine is the largest among all other halogens.(a) True(b) FalseI got this question by my school teacher while I was bunking the class.My doubt stems from Nature of C-X Bond in chapter Haloalkanes and Haloarenes of Chemistry – Class 12

Which of the following compounds contains an allylic carbon?(a) A(b) B(c) C(d) DThis question was addressed to me in a job interview.Query is from Haloalkanes Classification in chapter Haloalkanes and Haloarenes of Chemistry – Class 12