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1.

What is the major product formed when ethanol is dehydrated with concentrated H2SO4 at 413K?(a) Ethene(b) Methoxymethane(c) Methoxyethane(d) EthoxyethaneThe question was asked during an interview for a job.Query is from Ethers topic in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct answer is (d) Ethoxyethane

Best explanation: SYMMETRICAL ETHERS are formed when alcohols are dehydrated with H2SO4 at controlled temperatures. This is an SN2 reaction involving the attack of alcohol MOLECULE on a protonated alcohol to give ethers.

2.

Which of the following compounds is not used in the denaturation of alcohol?(a) Copper sulphate(b) Methyl alcohol(c) Pyridine(d) Ethyl alcoholThis question was posed to me during a job interview.This is a very interesting question from Commercially Important Alcohols topic in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct answer is (d) Ethyl alcohol

The best explanation: Ethyl alcohol is drinkable and is MADE unfit to drink to AVOID misuse in industries. This is DONE by adding some methanol, COPPER sulphate (to give it colour) and pyridine (to make it foul smelling). This is known as denaturation of alcohol.

3.

Which of the following is not a use of methanol?(a) Solvent for paints(b) Manufacturing of formaldehyde(c) Production of alcoholic drinks(d) Antifreeze in car radiatorsThe question was posed to me in class test.Question is taken from Commercially Important Alcohols in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct option is (c) Production of ALCOHOLIC drinks

Easy EXPLANATION: Methanol is HIGHLY poisonous and ingestion in small QUANTITIES can cause blindness and LARGE quantities can even lead to death.

4.

In the presence of air, phenols slowly start to form dark coloured mixtures.(a) True(b) FalseThe question was asked in semester exam.Origin of the question is Alcohols and Phenols in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct option is (a) True

To EXPLAIN I would say: Phenols are SLOWLY oxidised in the presence of AIR to form dark COLOURED mixtures containing quinones.

5.

The reaction between tert-Butyl chloride and sodium ethoxide gives _______(a) tert-Butyl ethyl ether(b) tert-Butyl methyl ether(c) 2-Methylprop-1-ene(d) buteneThis question was addressed to me by my school principal while I was bunking the class.Asked question is from Ethers topic in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right option is (c) 2-Methylprop-1-ene

Easy explanation: The reactant sodium ETHOXIDE is a strong nucleophile as well as a strong base, and hence elimination predominates over SN2 to form ALKENE as a major PRODUCT.

6.

What product(s) are formed when the shown ether is heated with hydrogen iodide?(a) (C6H5)CH2I and (C6H5)OH(b) (C6H5)CH2OH and (C6H5)I(c) (C6H5)CH2OH and (C6H5)CH2I(d) (C6H5)OH and (C6H5)IThe question was posed to me in a job interview.I'm obligated to ask this question of Ethers topic in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct CHOICE is (a) (C6H5)CH2I and (C6H5)OH

Explanation: The C-O bond of the phenol group is stronger than the C-O bond of the ether and ALKYL ARYL group. This is due to the partial double bond character because of sp^2 hybridised C-O cond. Therefore, the weaker C-O bond is broken and TWO MAJOR products, viz., phenol and iodomethyl benzene, are formed.

7.

Identify the major product of Friedel-Crafts acylation of anisole with ethanoyl chloride?(a) 2-Methoxytoluene(b) 4-Methoxytoluene(c) 2-Methoxyacetophenone(d) 4-MethoxyacetophenoneI got this question in semester exam.This key question is from Ethers in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct ANSWER is (d) 4-Methoxyacetophenone

Easiest explanation: Anisole undergoes Friedel-Crafts acylation where an acyl GROUP is INTRODUCED at ortho and para position by reaction with acyl chloride with anhydrous AlCl3 as catalyst. The para ISOMER will be the major product.

8.

The boiling point of ethers is ______ the boiling point of alcohols of comparable molecular mass.(a) lower than(b) similar to(c) little higher than(d) much higher thanThe question was asked by my school principal while I was bunking the class.Query is from Ethers topic in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer» CORRECT OPTION is (a) lower than

For explanation I would say: The large difference in boiling points of ALCOHOLS and ethers is DUE to the absence of INTERMOLECULAR bonds in the latter.
9.

Which alcohol is known as a wood spirit?(a) Methanol(b) Ethanol(c) Propanol(d) ButanolI got this question in final exam.This intriguing question comes from Commercially Important Alcohols in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right ANSWER is (a) Methanol

The best I can explain: Methanol was originally PRODUCED from the destructive DISTILLATION of WOOD and is hence, also known as wood spirit.

10.

Lucas test was conducted on three compounds A, B and C. Compounds A and B showed turbidity at room temperature, but compound C became turbid only after heating. Which of the compounds has a tertiary structure?(a) A(b) A and B(c) C(d) Cannot be determinedThis question was addressed to me by my school teacher while I was bunking the class.This interesting question is from Alcohols and Phenols in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right option is (d) Cannot be determined

For EXPLANATION: It is said that A and B show turbidity at room temperature, but it is not mentioned whether the appearance of turbidity is immediate or after some time. So compounds A and B may be tertiary or secondary depending on whether turbidity appears immediately or after 5 minutes RESPECTIVELY. Compound C is may be PRIMARY.

11.

Ethoxyethane is insoluble in water as compared to butanol.(a) True(b) FalseI got this question during an interview.Asked question is from Ethers topic in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right choice is (b) False

For EXPLANATION: ETHOXYETHANE and butanol have the same molecular mass and almost similar SOLUBILITIES in water, i.e., 7.5g for ethoxyethane and 9g for butanol per 100ML of water. This is because of the fact that even ethers can form hydrogen bonds with water MOLECULES just like the O of alcohols.

12.

Which of the following is not favourable for the proper dehydration of alcohol to form ether?(a) Good temperature control during reaction(b) Excess of alcohol(c) Presence of protic acids(d) Presence of bulky alkyl groups in the alcoholThis question was addressed to me in a job interview.This interesting question is from Ethers topic in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right option is (d) Presence of bulky alkyl groups in the alcohol

The best explanation: Secondary and tertiary alcohols give alkenes as major products during dehydration, because ELIMINATION COMPETES over substitution. Hence, this method is mainly used for PRIMARY alcohols.

13.

Ethers are linear molecules with zero dipole moment.(a) True(b) FalseI have been asked this question during an online interview.My question is based upon Ethers topic in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer» RIGHT OPTION is (b) False

To elaborate: Ethers have angular structures due to the polar nature of C-O bond because of the difference in electronegativity of C and O atoms. SINCE the two C-O bonds are inclined to each other at about 110°, the DIPOLE do not cancel out, and there is some dipole moment.
14.

Which of the following is the least reactive functional group?(a) Alcohols(b) Ethers(c) Aldehydes(d) KetonesI got this question during an interview for a job.The doubt is from Ethers topic in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right choice is (B) Ethers

The BEST I can explain: This is because the (-O-) group in ethers does not CONTAIN any active site as compared to for example, hydroxyl group (OH) in alcohols. However, they UNDERGO C-O bond cleavage in drastic conditions.

15.

Glucose and fructose are converted to ethanol in the presence of ________(a) invertase(b) zymase(c) oxidase(d) reductaseI got this question by my college director while I was bunking the class.This question is from Commercially Important Alcohols topic in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct answer is (b) zymase

Explanation: GLUCOSE and fructose undergo fermentation in the PRESENCE of an ENZYME called zymase, which is found in YEAST.

16.

Which of the following is not a property of methanol?(a) Colourless liquid(b) Boiling point 337K(c) Immiscible in water(d) Highly poisonousI had been asked this question in an interview for internship.My query is from Commercially Important Alcohols in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct answer is (C) Immiscible in WATER

Easiest EXPLANATION: Methanol is a COLOURLESS LIQUID that boils at 337K. It is miscible in water in all proportions.

17.

What is the major product of bromination of anisole in ethanoic acid?(a) o-Dibromobenzene(b) p-Dibromobenzene(c) o-Bromoanisole(d) p-BromoanisoleI had been asked this question in an interview for job.I'm obligated to ask this question of Ethers topic in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct option is (d) p-Bromoanisole

Explanation: Phenyl alkyl ethers undergo bromination in the BENZENE ring with bromine in ETHANOIC acid. This due to the activation of benzene ring by OCH3 group and its ORTHO, para directing effect. The para ISOMER is OBTAINED in 90% yield.

18.

One molecule of dialkyl ether produces how many molecules of alkyl halides with excess of halogen acid?(a) 1(b) 2(c) 3(d) 4The question was posed to me in semester exam.My question comes from Ethers in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct option is (b) 2

To explain: DIALKYL ethers when TREATED with excess halogen acid first FORM an alkyl HALIDE and alcohol. The alcohol further reacts with the excess acid to form the same alkyl halide and a water molecule. Thus, two alkyl halide MOLECULES are produced in the end.

19.

Which of the following is the most suitable requirement for the dehydration of ethanol to form an ether?(a) Sulphuric acid at 413K(b) Sulphuric acid at 443K(c) Sodium hydroxide at 413K(d) Sodium hydroxide at 443KI got this question during a job interview.This interesting question is from Ethers topic in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct answer is (a) Sulphuric acid at 413K

For EXPLANATION: Alcohols undergo dehydration in the presence of protic acids to FORM EITHER alkenes or ethers depending upon the reaction TEMPERATURE conditions. At 413K, ethanol forms an ether with H2SO4.

20.

Methanol can be used as an antiseptic in hospitals.(a) True(b) FalseI had been asked this question at a job interview.The question is from Commercially Important Alcohols in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct answer is (b) False

To explain I would SAY: Methanol is harmful in NATURE and HUMAN CONTACT should be avoided at all times. HOWEVER, ethanol can be used as an antiseptic.

21.

Which of the following is the most suitable temperature and pressure conditions for production of methanol by catalytic hydrogenation?(a) 300K, 100atm(b) 400K, 250atm(c) 500K, 275atm(d) 600K, 300atmI got this question during an interview.My question comes from Commercially Important Alcohols in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct OPTION is (d) 600K, 300atm

For explanation I would say: Methanol is produced by CATALYTIC hydrogenation of carbon monoxide at high PRESSURE (200-300atm) and high temperature (573-673K) in the PRESENCE of ZnO-Cr2O3 catalyst.

22.

Sodium methoxide on heating with bromoethane gives __________(a) methoxymethane(b) methoxyethane(c) ethoxyethane(d) diethyl etherThe question was posed to me during an interview.Question is taken from Ethers topic in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct CHOICE is (b) methoxyethane

To EXPLAIN I would say: This is an EXAMPLE of Williamson synthesis of unsymmetrical ether, where CH3ONa is reacted with CH3CH2Br to form CH3CH2OCH3, which is ethyl methyl ether.

23.

4-Nitroanisole is obtained as the major product when anisole reacts with _____(a) concentrated H2SO4(b) concentrated HNO3(c) mixture of concentrated H2SO4 and HNO3(d) mixture of dilute H2SO4 and HNO3The question was asked during a job interview.I would like to ask this question from Ethers topic in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct CHOICE is (C) mixture of concentrated H2SO4 and HNO3

Easy explanation: Anisole undergoes nitration in the presence of concentrated ACIDS H2SO4 and HNO3 to yield a mixture of ortho and para nitroanisoles.

24.

Which compound can covert phenol back to benzene?(a) CrO3(b) Zinc dust(c) Pyridine(d) Strong acidI had been asked this question by my school principal while I was bunking the class.Query is from Alcohols and Phenols in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer» CORRECT choice is (B) Zinc dust

The best I can explain: When HEATED with zinc dust, the C-O bond in phenol is broken and it is reduced to BENZENE and zinc OXIDE.
25.

In wine making, the sugar required is derived from which source?(a) Sugarcane(b) Molasses(c) Grapes(d) InvertaseThis question was addressed to me in a national level competition.Origin of the question is Commercially Important Alcohols topic in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct choice is (c) Grapes

The BEST explanation: Grapes are the source of sugar as well as yeast in wine making. As the grapes RIPEN, the quantity of sugar INCREASES and yeast grows on the OUTSIDE.

26.

Which of the following compounds gives a ketone when its vapours are passes over heated copper at 573K?(a) Propan-1-ol(b) Propan-2-ol(c) 2-Methylpropan-1-ol(d) 2-Methylpropan-2-olI have been asked this question in my homework.Enquiry is from Alcohols and Phenols in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct option is (b) Propan-2-ol

Best explanation: Secondary ALCOHOLS UNDERGO dehydrogenation when its vapours are passed over Cu at 573K to give ketone. Primary and TERTIARY alcohols under the same conditions give ALDEHYDES and ALKENES respectively.

27.

Water is a ______ than alcohol.(a) better proton acceptor(b) stronger base(c) weaker acid(d) better proton donorThis question was addressed to me in a national level competition.This is a very interesting question from Alcohols and Phenols in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right choice is (d) better proton donor

To EXPLAIN: The REACTION between water and an alkoxide illustrates that water is a better proton donor (stronger ACID) than ALCOHOL.

28.

Which of the following oxidising agents is used to obtain carboxylic acids directly from alcohols?(a) Acidified KMnO4(b) Aqueous KMnO4(c) Alkaline KMnO4(d) Anhydrous CrO3This question was addressed to me during an interview.I want to ask this question from Alcohols and Phenols topic in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The CORRECT answer is (a) Acidified KMnO4

Explanation: Strong OXIDISING AGENTS like acidified POTASSIUM permanganate or acidified potassium dichromate convert alcohol directly to carboxylic acid. However, only aldehyde can be obtained by using CrO3 as the oxidising agent in an anhydrous medium.

29.

What is the catalyst used in the acetylation of alcohols?(a) Palladium(b) Hydrogen peroxide(c) Pyridine(d) Aluminium chlorideThe question was asked in an interview.This interesting question is from Alcohols and Phenols topic in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct choice is (C) Pyridine

Easy explanation: The reaction of alcohols with acid chlorides and acid anhydride is carried out in the presence of a base so as to neutralise the acid FORMED during the reaction. This facilitates the shift f EQUILIBRIUM in the FORWARD DIRECTION.

30.

Four compounds A, B, C and D having similar molecular masses were tested for their boiling points. It was found that compound C has the highest boiling point of all four. What is the compound C most likely to be?(a) Hydrocarbon(b) Haloalkane(c) Alcohol(d) EtherI have been asked this question in an international level competition.This intriguing question originated from Alcohols and Phenols in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct option is (c) Alcohol

For EXPLANATION: Of compounds having similar molecular masses, alcohols will CERTAINLY have the highest boiling POINT due to the presence of intermolecular hydrogen BONDING which is lacking in hydrocarbons, haloalkanes and ETHERS.

31.

Identify the compound ‘X’.(a) Oleum(b) Sulphuric acid(c) Nitrous acid(d) Sodium sulphateI had been asked this question in homework.My query is from Alcohols and Phenols topic in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct choice is (a) Oleum

Best EXPLANATION: Oleum is a mixture of H2SO4 and SO3 that is added to benzene to form benzene sulphonic acid, which on subsequent treatment as SHOWN, gives phenol.

32.

How is carbolic acid prepared from benzene diazonium chloride?(a) Treating it with nitrous acid at 275K(b) Preparing an aqueous solution and warming it(c) Treating it with sodium hydroxide(d) Freezing itThis question was addressed to me by my school principal while I was bunking the class.This interesting question is from Alcohols and Phenols topic in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The CORRECT answer is (b) Preparing an aqueous solution and warming it

Explanation: CARBOLIC acid is another NAME for phenol. Simply warming an aqueous solution of benzene DIAZONIUM chloride salt or treating it with a DILUTE acid, will result in the formation of phenol.

33.

What happens when an aldehyde is treated with lithium aluminium hydride?(a) Primary alcohol is formed(b) Secondary alcohol is formed(c) Tertiary alcohol is formed(d) No reactionThis question was posed to me in an interview for internship.My question is from Alcohols and Phenols topic in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The CORRECT answer is (a) PRIMARY alcohol is formed

Easy explanation: LiAlH4 acts as a REDUCING agent which reduces an aldehyde by adding hydrogen atoms to it result in the formation of a primary alcohol.

34.

Which carbonyl compound yields secondary alcohols when treated with LiAlH4?(a) Aldehyde(b) Ketone(c) Carboxylic acid(d) EsterI got this question in class test.The question is from Alcohols and Phenols in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct CHOICE is (B) Ketone

Explanation: Ketones react with reducing AGENTS LiAlH4 or NaBH4 to get reduced to alcohol where the OH GROUP is formed at the C of the C-O group. This results in the C being bonded to two alkyl GROUPS apart from the OH and H atom.

35.

Which of the following is an incorrect name for the compound with aromatic ring having hydroxyl groups at para positions?(a) Hydroquinone(b) Benzene-1,4-diol(c) Resorcinol(d) QuinolI had been asked this question during an online exam.This question is from Alcohols, Phenols and Ethers Nomenclature topic in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right answer is (c) Resorcinol

The best EXPLANATION: Resorcinol is the common NAME for the dihydric phenolic COMPOUND with the OH GROUPS at meta positions or 1, 3 positions.

36.

If the dipole moment of methanol is 1.71D, predict the dipole moment of phenol.(a) 1.54D(b) 1.71D(c) 1.89D(d) 1.96DThe question was asked in exam.The question is from Structures of Functional Groups in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer» RIGHT answer is (a) 1.54D

The explanation: Phenol has a smaller dipole moment than methanol because the C-O bond in phenols is POLAR due to the electron withdrawing EFFECT of the aromatic RING.
37.

The oxidation of alcohol involves the cleavage of _____ bonds.(a) O-H(b) C-H(c) O-H and C-H(d) HydrogenThis question was posed to me during an interview.My question is taken from Alcohols and Phenols topic in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right ANSWER is (c) O-H and C-H

Explanation: Oxidation of alcohols involves the cleavage of both O-H and C-H bonds so as to form a carbon-oxygen DOUBLE bond. This RESULTS in the release of dihydrogen and as a RESULT is also known as DEHYDROGENATION reactions.

38.

Phenols are stronger acids than alcohols.(a) True(b) FalseThis question was addressed to me during an interview.My question is taken from Alcohols and Phenols topic in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right answer is (a) True

The BEST explanation: The aryl CARBON in phenols is more electronegative than the sp^3 hybridized carbon in alcohols due to the presence of double BOND. This EXTRA negative charge is also delocalized at positions across the benzene, resulting in RESONATING structure and hence stability.

39.

The first step of the acid catalysed hydration of alkenes, involves the protonation of alkene to form a carbocation by electrophilic attack of _______(a) H^+(b) H2O(c) H3O^+(d) OH^–I have been asked this question in examination.Origin of the question is Alcohols and Phenols in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The CORRECT choice is (c) H3O^+

For EXPLANATION: The water reacts with the H^+ ion of the MINERAL acid to form a hydronium ion (H3O^+). This ion attacks the CARBON double bond to form a carbocation and give a water molecule.

40.

Which of the following is not a correct reason for the C-O bond length in phenol to be less than that in methanol?(a) Partial double bond character of C-O bond(b) Conjugation of lone pair of electrons with the aromatic ring(c) sp^2 hybridised sate of carbon of C-O bond(d) Repulsion between the electron lone pairs of oxygenI had been asked this question by my school teacher while I was bunking the class.Query is from Structures of Functional Groups topic in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The CORRECT choice is (d) Repulsion between the electron lone PAIRS of oxygen

The BEST explanation: The two lone pairs of ELECTRONS of oxygen are present in OH groups of both phenol and methanol and has an effect on the C-O-H bond angle and not the C-O bond length.

41.

Which of the following is true regarding polyhydric alcohols?(a) It should have one or more OH groups(b) It should have two or more OH groups(c) It should have three or more OH groups(d) It should have more than four OH groupsThis question was addressed to me during an online interview.This is a very interesting question from Alcohols, Phenols and Ethers Classification in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct option is (b) It should have two or more OH groups

The explanation is: ALCOHOLS may be classified as mono-, di- TRI- or polyhydric depending on whether it has ONE, two, three or more OH groups in its structure. Di- and trihydric alcohols are ALSO classified as polyhydric.

42.

Propan-2-ol undergoes acidic dehydration relatively at a lower temperature than propan-1-ol.(a) True(b) FalseThis question was addressed to me in quiz.My query is from Alcohols and Phenols topic in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct option is (a) True

The explanation is: Acidic DEHYDRATION of alcohols occurs through the formation of a CARBOCATION. Since tertiary alcohol produce the most STABLE carbocations and PRIMARY alcohols produce the least stable carbocation, the dehydration of tertiary and secondary alcohols is relatively easier.

43.

If the boiling point of methoxymethane is 248K, predict the boiling point of ethanol.(a) 231K(b) 248K(c) 351K(d) 455KI have been asked this question during an online interview.This interesting question is from Alcohols and Phenols topic in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right option is (c) 351K

The best I can explain: Methoxymethane and ethanol are of COMPARABLE masses and it can be easily pointed out that ethanol will have a higher boiling point than it because of the presence of INTERMOLECULAR HYDROGEN bonding. 455K is very high and is actually the boiling point of PHENOL.

44.

Phenol is approximately how much times acidic than ethanol?(a) 10(b) 25(c) 100(d) millionThe question was asked in an interview for job.I want to ask this question from Alcohols and Phenols in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct choice is (d) million

Best explanation: Phenol is more acidic than ALCOHOLS because of their better STABILITY and RESONANT structures. The pKa values of phenol and ethanol are 10 and 15.9 respectively, which when converted to Ka values gives a RATIO of about a million.

45.

Which of the following isomeric alcohols is the most soluble in water?(a) n-Butyl alcohol(b) Isobutyl alcohol(c) sec-Butyl alcohol(d) tert-Butyl alcoholThis question was posed to me by my school teacher while I was bunking the class.My query is from Alcohols and Phenols in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right OPTION is (d) tert-Butyl ALCOHOL

For explanation: tert-Butyl alcohol is the most heavily branched isomer and is tightly PACKED compared to the OTHERS. This decreases the effective surface area of the alkyl part which is HYDROPHOBIC in nature.

46.

The name 1-Ethoxy-2, 2-dimethylcyclohexane is correct according to IUPAC nomenclature.(a) True(b) FalseThe question was posed to me by my school teacher while I was bunking the class.This is a very interesting question from Alcohols, Phenols and Ethers Nomenclature topic in portion Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

The correct answer is (B) False

Explanation: The METHYL GROUP should be GIVEN higher preference over the alkoxy group in ETHERS. The correct naming will be 2-Ethoxy-1, 1-dimethylcyclohexane.

47.

Which of the following is incorrect regarding Kolbe’s reaction?(a) The final product is Salicylic acid(b) CO2 acts as an electrophile(c) Acidification of phenol leads to formation of main product(d) Phenoxide ion undergoes electrophilic attackThis question was addressed to me in my homework.My question is based upon Alcohols and Phenols topic in section Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right choice is (c) ACIDIFICATION of phenol leads to FORMATION of main product

Explanation: The first step of KOLBE’s reaction is the formation of sodium phenoxide, which is formed by TREATING phenol with NaOH. This phenoxide undergoes substitution by a weak electrophile, CO2, to form the main product, i.e., 2-Hydroxybenzoic acid or salicylic acid.

48.

Alcohols and phenols are ________(a) Lewis acids(b) Lewis bases(c) Bronsted acids(d) Bronsted basesThe question was asked by my college professor while I was bunking the class.Enquiry is from Alcohols and Phenols in division Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Right ANSWER is (c) Bronsted acids

The best I can explain: Alcohols and phenols are known to be ACIDIC in nature based on their interaction with metals. They are able to DONATE a proton to a stronger base. Additionally, alcohols ALSO act as Bronsted bases due to the presence of unshared electron PAIRS on oxygen.

49.

What is the correct order of boiling points of alcohols having the same number of carbon atoms?(a) 1°>2°>3°(b) 3°>2°>1°(c) 3°>1°>2°(d) 2°>1°>3°The question was asked in homework.This interesting question is from Alcohols and Phenols in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct answer is (a) 1°>2°>3°

Easy explanation: As the branching in the structure increases, the surface AREA decreases and hence, the van der Waal FORCES decrease. This results in the reduction of boiling POINTS of isomeric alcohols from primary to tertiary STRUCTURES.

50.

Which of the following is necessary for the bromination of phenol?(a) CS2(b) FeBr3(c) AlCl3(d) BF3This question was posed to me in an interview for internship.Asked question is from Alcohols and Phenols in chapter Alcohols, Phenols and Ethers of Chemistry – Class 12

Answer»

Correct answer is (a) CS2

Explanation: FeBr3, AlCl3 and BF3 are LEWIS ACIDS, that are REQUIRED for the substitution in benzene. Phenol has an OH group that activates the aromatic ring and requires the presence of only SLIGHTLY or non-polar SOLVENTS for its halogenation.