158 + Interview Questions in Aldehydes in Chemistry – Class 12 Page 2 InterviewSolution

51.	What is the correct IUPAC name of the shown compound?(a) 2-Carboxylmethylcyclopentane(b) 2-Methylcyclopentanecarboxylic acid(c) 2-Methylcyclopentanoic acid(d) (2-Methylcyclopentyl)carboxylic acidI had been asked this question during an interview.Question is taken from Nomenclature and Structure of Carboxyl Groups topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» CORRECT option is (B) 2-Methylcyclopentanecarboxylic acid Easiest explanation: The compound is a cyclic carboxylic acid with five carbon atoms in the cyclic RING and one carboxyl group. The methyl group is present as a substituent at the ADJACENT position on the ring. Hence, it is NAMED as a derivative of cyclopentanecarboxylic acid.

Discussion

52.	What is the correct IUPAC name of the compound CH3CH=CHCH=CHCOOH?(a) Hexenedioc acid(b) Hexa-2,4-dienoic acid(c) Penta-1,3-dienioc acid(d) Pentenedioc acidI have been asked this question by my school principal while I was bunking the class.I want to ask this question from Nomenclature and Structure of Carboxyl Groups topic in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct option is (b) Hexa-2,4-dienoic acid To explain I WOULD say: The COMPOUND consists of six CARBON atoms including the carboxyl carbon thus, it is a derivative of hexanoic acid. The only substituents are two double bonds at the second and FOURTH carbon considering that the carboxyl carbon is the number one.

Discussion

53.	Which of the following is not a use of formaldehyde?(a) Preservation of biological specimens(b) Manufacturing of bakelite(c) Silvering of mirrors(d) Preparation of acetic acid.This question was addressed to me by my college professor while I was bunking the class.Asked question is from Uses of Aldehydes and Ketones in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right choice is (d) PREPARATION of acetic acid. For explanation I would say: Formaldehyde consists of only a single CARBON atom and cannot be USED as a starting compound for the preparation of acetic acid. However, it is used in the manufacture of bakelite, glues and polymeric products. It also ACTS as a reducing agent in the silvering of MIRRORS.

Discussion

54.	Benzoic acid reacts with ______ to give ammonium benzoate salt, which on further dehydration gives benzamide.(a) N2(b) NH3(c) NH4OH(d) HNO3The question was asked during a job interview.My doubt is from Carboxylic Acids Chemical Reactions topic in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct choice is (b) NH3 Best explanation: Benzoic acid reacts with AMMONIA in a reversible REACTION to form ammonium benzoate by addition reaction. This salt then loses water on HEATING to form BENZAMIDE.

Discussion

55.	Which is the most preferred reagent in the product of acetyl chloride from acetic acid?(a) Cl2(b) PCl3(c) PCl5(d) SOCl2The question was asked in an online interview.I want to ask this question from Carboxylic Acids Chemical Reactions topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct answer is (d) SOCl2 Easiest explanation: Thionyl chloride REACTS with acetic acid to form ACETYL chloride ALONG with two GASEOUS compounds (SO2 and HCL) that escape the reaction mixture, making the purification of the product easier.

Discussion

56.	Which of the following is the stronger acid?(a) Acetic acid(b) Propanoic acid(c) Isobutyric acid(d) 2,2-Dimethylpropanoic acidThe question was asked during an interview for a job.My question is taken from Carboxylic Acids Chemical Reactions topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct CHOICE is (a) Acetic acid Best EXPLANATION: As the size of alkyl group (electron releasing) increases, the electron density on the O of OH group increases, and makes release of H^+ ion more difficult. Thus, the release of proton from acetic acid will be easier compared to the higher acids, and is therefore the stronger acid.

Discussion

57.	3-Chlorophenyl magnesium bromide on reaction with dry ice followed by acidification in mineral acid gives _________(a) 3-Chlorophenol(b) 3-Chlorophenylethanoic acid(c) 3-Chlorobenzaldehyde(d) 3-Chlorobenzoic acidI had been asked this question during an interview.This interesting question is from Methods of Carboxylic Acids Preparation topic in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» CORRECT choice is (d) 3-Chlorobenzoic acid To explain I would say: The MgBr group of 3-Chlorophenyl magnesium BROMIDE (Grignard reagent) will be substituted by COOH group in the above reaction, to GIVE a HALOGEN substituted aromatic carboxylic acid.

Discussion

58.	Acetaldehyde is oxidised to ______ in the presence of nitric acid.(a) methanoic acid(b) ethanoic acid(c) acetone(d) ethanolI had been asked this question during an interview.I want to ask this question from Aldehydes and Ketones Chemical Reactions topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct option is (B) ethanoic acid Explanation: Aldehydes are EASILY oxidised to carboxylic ACIDS with same number of carbon atoms, in the presence of oxidising agents like HNO3, KMnO4, etc. This is because of the presence of H atom next to CO group, which can be easily converted to OH group with any bond cleavage.

Discussion

59.	The nucleophilic addition reactions of aldehydes are carried out in ________ medium.(a) neutral(b) acidic(c) weakly basic(d) extremely basicThis question was addressed to me in a national level competition.This intriguing question comes from Aldehydes and Ketones Chemical Reactions in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct answer is (b) ACIDIC Explanation: When the incoming nucleophile is weak, the acidic MEDIUM helps in protonation by INCREASING the POSITIVE charge on the carbonyl carbon so that it is more susceptible to attack by RELATIVELY weaker nucleophiles.

Discussion

60.	Acetyl chloride reacts with _______ to give butan-2-one.(a) cadmium chloride(b) methyl magnesium chloride(c) dimethyl cadmium(d) diethyl cadmiumI have been asked this question in exam.My question is from Preparation of Aldehydes and Ketones topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right option is (d) diethyl cadmium The explanation: For butan-2-one to form from acetyl chloride, the CL group NEEDS to be REPLACED by an ethyl group. This ethyl group is obtained from diethyl cadmium which is produced from the reaction between ethyl MAGNESIUM bromide and cadmium chloride.

Discussion

61.	Which of the following reactions can produce ketones?(a) Oxidation of primary alcohols(b) Dehydrogenation of primary alcohols(c) Dehydrogenation of tertiary alcohols(d) Oxidation of secondary alcoholsI got this question during an internship interview.I need to ask this question from Preparation of Aldehydes and Ketones topic in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right ANSWER is (d) OXIDATION of secondary ALCOHOLS The explanation: Oxidation and DEHYDROGENATION of secondary alcohols results in ketones. The same reactions with primary alcohols give aldehydes.

Discussion

62.	What is the approximate planar bond angle between the carbonyl C-O bond and the bond between the carbonyl carbon and the atom attached to it?(a) 60°(b) 90°(c) 120°(d) 135°The question was asked by my college director while I was bunking the class.I would like to ask this question from Nomenclature and Structure of Carbonyl Groups in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct CHOICE is (C) 120° Explanation: The BOND angles ASSOCIATED with the CARBONYL group is approximately 120°, which is similar to that of a trigonal coplanar structure.

Discussion

63.	The compound 3-Phenylprop-2-enal is also known as _________(a) Crotonaldehyde(b) Cinnamaldehyde(c) Salicylaldehyde(d) VanillinThis question was addressed to me during an interview.My doubt stems from Nomenclature and Structure of Carbonyl Groups in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct choice is (b) CINNAMALDEHYDE The best I can explain: In cinnamaldehyde, a BENZENE RING is attached to the end carbon of the ALDEHYDE chain and also has a carbon double bond at the alpha carbon. Its formula is C6H5-CH=CH-CHO.

Discussion

64.	Which of the following compounds do not contain a carbonyl group?(a) Alcohol(b) Aldehyde(c) Ketone(d) Carboxylic acidI got this question in final exam.My question is from Nomenclature and Structure of Carbonyl Groups in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» CORRECT option is (a) Alcohol Easiest explanation: CARBONYL groups are those which CONTAIN a carbon-oxygen double BOND. In alcohols, the bond between C and O is a single bond and hence does not contain a carbonyl group.

Discussion

65.	What is the IUPAC name of the following compound?(a) 6-(2-oxocyclohexyl)-hexan-3-one(b) 2-(3-oxopentyl)-cyclohexan-1-one(c) 2-(4-oxopentyl)-cyclohexan-1-one(d) 5-(2-oxocyclohexyl)-hexan-3-oneI had been asked this question during an interview.This interesting question is from Nomenclature and Structure of Carbonyl Groups in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct choice is (b) 2-(3-oxopentyl)-cyclohexan-1-one The best explanation: The cyclic ketone is CONSIDERED as the main GROUP with the 3-oxopentyl keto group substituted at ALPHA carbon.

Discussion

66.	If the boiling point of propanol is 370 K, predict the boiling point of acetic acid.(a) 322 K(b) 329 K(c) 370 K(d) 390 KI have been asked this question during a job interview.Enquiry is from Carboxylic Acids Physical Properties topic in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right choice is (d) 390 K The BEST explanation: Acetic acid and propanol both have same molecular mass. Acetic acid should have a HIGHER boiling point than propanol because of its stronger hydrogen bonds and the FACT that it forms cyclic DIMERS.

Discussion

67.	Acidic hydrolysis of ethyl benzoate directly gives benzoic acid.(a) True(b) FalseI had been asked this question in an online quiz.This intriguing question comes from Methods of Carboxylic Acids Preparation topic in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right ANSWER is (a) True Explanation: Acidic hydrolysis of esters directly gives carboxylic ACIDS. In this case, the ethyl group of the ESTER is SEPARATED out as ethanol along with the main product, BENZOIC acid.

Discussion

68.	Which of the following carbonyl compounds are known for their pleasant odour?(a) Vanillin(b) Acetophenone(c) Acetone(d) CamphorThe question was posed to me in unit test.I want to ask this question from Uses of Aldehydes and Ketones topic in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» RIGHT answer is (C) Acetone Explanation: Acetone belongs to the lower sizes of ketones and is LESS fragrant than the higher compounds LIKE acetophenone, CAMPHOR and vanillin which are used as flavouring agents in different industries.

Discussion

69.	Which of the following is used in the preservation of biological specimens?(a) Methanal(b) Ethanal(c) Acetone(d) BenzaldehydeI got this question in an online quiz.This intriguing question comes from Uses of Aldehydes and Ketones in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct answer is (a) Methanal To EXPLAIN I would say: Methanal is EASILY SOLUBLE in water and is commercially sold as formalin (40% methanal, 8% methanol, 52% water) and is used for preserving BIOLOGICAL specimens.

Discussion

70.	Identify the N-substituted derivative of carbonyl compounds that are coloured compounds and are useful in the identification of aldehydes and ketones.(a) Hydrazone(b) Phenylhydrazone(c) 2,4-Dinitrophenylhydrazone(d) SemicarbazoneThis question was posed to me in an internship interview.I'm obligated to ask this question of Aldehydes and Ketones Chemical Reactions in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right answer is (C) 2,4-Dinitrophenylhydrazone Best explanation: 2,4-DNP derivatives are formed from the reaction between aldehydes or ketones and 2,4-Dinitrohydrazine. These products may be YELLOW, orange or ED COLOURED and help in characterisation of aldehydes and ketones.

Discussion

71.	Which of the following is the least soluble in water?(a) Methanal(b) Ethanal(c) Propanone(d) PentanalI got this question in my homework.My question is from Aldehydes and Ketones Physical Properties topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct CHOICE is (d) Pentanal For explanation I would say: The lower aldehydes and ketones are miscible in water in all proportions DUE to the ability of the polar carbonyl group to form hydrogen bonds with water molecules. HOWEVER, the solubility rapidly decreases as the length of the alkyl chain increases. PRECISELY, aldehydes and ketones with more than 4 carbon ATOMS are practically insoluble in water.

Discussion

72.	What is the IUPAC name of CH3-CO-CH2-CH2-CH3?(a) Butan-1-one(b) Butan-2-one(c) Pentan-1-one(d) Pentan-2-oneThe question was posed to me in exam.Query is from Nomenclature and Structure of Carbonyl Groups in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct answer is (d) Pentan-2-one The explanation: The CARBON of the CO ketonic group should be INCLUDED in the parent chain, and the numbering starts from the end nearer to the carbonyl group. Hence in the GIVEN COMPOUND, there are five carbon atoms in the parent chain and the carbonyl carbon is second one.

Discussion

73.	Friedel-Crafts benzoylation of benzene gives ________(a) acetophenone(b) propiophenone(c) benzophenone(d) no reactionI have been asked this question in exam.My question comes from Preparation of Aldehydes and Ketones in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct answer is (c) BENZOPHENONE The EXPLANATION: When benzene is treated with BENZOYL chloride in the presence of anhydrous ALUMINIUM chloride, it forms benzophenone which is an aromatic ketone.

Discussion

74.	Identify the correct IUPAC name of the following compound.(a) 3-Methylcyclopent-2-en-1-one(b) 1-Methylcyclopent-1-en-3-one(c) Cyclo-1-methyl-pent-1-en-3-one(d) Cyclo-3-methyl-pent-2-en-1-oneThe question was asked in an internship interview.I need to ask this question from Nomenclature and Structure of Carbonyl Groups in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» CORRECT answer is (a) 3-Methylcyclopent-2-en-1-one To ELABORATE: This is a cyclic ketone with a DOUBLE bond and a SUBSTITUTED methyl group. In this compound the keto carbon will be given the lowest number. Hence, the double bond is at second carbon and methyl group at the third carbon. It is named as a substituted CYCLOPENTANONE.

Discussion

75.	Which carboxylic acid is used in the manufacturing of nylon-6,6?(a) Propanedioic acid(b) Butanedioic acid(c) Pentanedioic acid(d) Hexanedioic acidI had been asked this question by my college professor while I was bunking the class.The question is from Uses of Carboxylic Acids in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct answer is (d) Hexanedioic ACID Easiest EXPLANATION: Nylon-6,6 is MANUFACTURED from the condensation polymerisation of hexanedioic acid (ADIPIC acid) with hexamethylenediamine under high pressure and temperature.

Discussion

76.	Benzoic ethanoic anhydride on hydrolysis gives __________(a) benzoic acid and methanoic acid(b) benzoic acid and ethanoic acid(c) phenylethanoic acid and methanoic acid(d) no productsI had been asked this question in a job interview.The origin of the question is Methods of Carboxylic Acids Preparation topic in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct ANSWER is (b) benzoic acid and ethanoic acid Best explanation: Benzoic ethanoic anhydride (C6H5COOCOCH3) is EASILY HYDROLYSED with water to give its CORRESPONDING acids, benzoic acid (by adding H to C6H5COO) and ethanoic acid (by adding OH to COCH3).

Discussion

77.	Ammonium acetate on removal of ______ forms acetamide.(a) H2(b) NH3(c) OH^–(d) H2OThe question was posed to me in an interview for job.Asked question is from Carboxylic Acids Chemical Reactions in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct OPTION is (d) H2O Easiest EXPLANATION: Ammonium acetate (CH3COO-NH4^+) is an ammonium salt which on heating at HIGH temperatures, loses a water molecule to give acetamide (CH3CONH2).

Discussion

78.	p-Xylene on reaction with acidified potassium dichromate at high temperature gives ________(a) benzoic acid(b) phthalic acid(c) terephthalic acid(d) no reactionThe question was asked in class test.This question is from Methods of Carboxylic Acids Preparation in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct CHOICE is (c) terephthalic acid For EXPLANATION I would say: p-Xylene is a dimethyl substituted benzene which on vigorous oxidation, gets oxidised to an AROMATIC dicarboxylic acid, with the two carboxyl GROUPS at para positions with RESPECT to each other. This compound is called terephthalic acid.

Discussion

79.	Which of the following products is formed when an aldehyde reacts with an amine in acidic medium?(a) Imine(b) Schiff’s base(c) Oxime(d) HydrazoneThe question was posed to me in quiz.My query is from Aldehydes and Ketones Chemical Reactions topic in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right answer is (b) SCHIFF’s base The explanation is: Amine is a nucleophile and a derivative of NH3 which react with aldehydes and ketones followed by DEHYDRATION to form compounds with C-N double BOND CALLED Schiff’s base or SUBSTITUTED imines.

Discussion

80.	What is the correct IUPAC name of α-Methylcyclohexanone?(a) Methylcyclohexanone(b) Methylcyclohexan-2-one(c) 2-Methylcyclohexanone(d) Cyclomethylhexan-2-oneThis question was addressed to me in an interview.The query is from Nomenclature and Structure of Carbonyl Groups in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct answer is (c) 2-Methylcyclohexanone For EXPLANATION I would SAY: Alpha represents the presence of a substituent on the carbon next to the carbon of the CO group. The ketone group is given the lower number in CASE of substituted KETONES hence the number 2 is associated with the methyl group in this case.

Discussion

81.	What is the common name of butanal?(a) n-Butanaldehyde(b) α-Butanaldehyde(c) n-Butyraldehyde(d) α-ButyraldehydeThe question was asked in examination.Question is from Nomenclature and Structure of Carbonyl Groups in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct answer is (C) n-Butyraldehyde Explanation: Butanal is a straight chain ALDEHYDE with 4 carbon ATOMS including the carbonyl GROUP. There is no substituent present in the carbon chain and hence the prefix n- is given in the common name.

Discussion

82.	Ethanoic acid is used as vinegar in the cooking industry.(a) True(b) FalseThis question was posed to me during an online interview.I'd like to ask this question from Uses of Carboxylic Acids in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct option is (a) True Easiest explanation: Generally, a 1:10 solution of acetic acid in water is CALLED VINEGAR. It is a commercial product that may be used in SALADS or other foods. It may include traces of other chemicals for the need of flavouring.

Discussion

83.	Soda lime consists of NaOH and CaO respectively, in the ratio of _______(a) 1:2(b) 2:1(c) 1:3(d) 3:1I had been asked this question in examination.The doubt is from Carboxylic Acids Chemical Reactions topic in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» CORRECT choice is (d) 3:1 Easy explanation: Soda LIME is the 3:1 mixture of sodium hydroxide and CALCIUM oxide, and is used in the decarboxylation reaction (loss of carbon dioxide) of carboxylic ACIDS.

Discussion

84.	Which of the following is an incorrect name for the following compound?(a) α-Methylpropionic acid(b) β-Methylbutyric acid(c) Isovaleric acid(d) 3-Methylbutanoic acidI got this question in an internship interview.Question is from Nomenclature and Structure of Carboxyl Groups topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct answer is (a) α-Methylpropionic acid For explanation: The longest PARENT chain of carbon atoms (including the first carboxyl carbon) is FOUR. The methyl group is substituted at the THIRD carbon, also known as the beta carbon. Isovaleric acid is also a COMMON name for this structure.

Discussion

85.	Identify the correct IUPAC name of the following compound?(a) 4-Oxocyclohexan-1-carboxylic acid(b) 4-Carboxylcyclohexan-1-one(c) 4-Oxocyclohexylmethanoic acid(d) 4-Oxocyclohexylethanoic acidThis question was addressed to me in examination.Enquiry is from Nomenclature and Structure of Carboxyl Groups topic in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct OPTION is (a) 4-Oxocyclohexan-1-carboxylic acid Easiest EXPLANATION: This is a keto-substituted cyclic carboxylic acid and is named considering the CO group as a substituent at the fourth position given that the carbon attached to the CARBOXYL carbon is C-1.

Discussion

86.	The hydrolysis of the addition product of acetone and methyl magnesium iodide gives _______(a) ethyl alcohol(b) isopropyl alcohol(c) tert-Butyl alcohol(d) phenolI have been asked this question in an interview for internship.Question is from Aldehydes and Ketones Chemical Reactions in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct choice is (c) tert-Butyl ALCOHOL To explain: The methyl group of Grignard reagent is the nucleophile which initially GET attached to the carbonyl carbon of acetone. This results in THREE methyl groups attached to the carbon atom and one OMgI group. This MgI is replaced by H^+ on HYDROLYSIS to give tert-Butyl alcohol. Similarly, methanal gives ethyl alcohol (1°) and other aldehydes give 2° alcohols.

Discussion

87.	What is formed after the hydrolysis of the product of the reaction between benzonitrile and methyl magnesium bromide in dry ether?(a) Phenyl acetaldehyde(b) Acetophenone(c) 1-Phenylpropanone(d) BenzaldehydeThis question was addressed to me in my homework.The origin of the question is Preparation of Aldehydes and Ketones in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» RIGHT ANSWER is (B) Acetophenone The best I can explain: When a nitrile is treated with a Grignard reagent in the presence of dry ether, an addition product is formed which on hydrolysis GIVES a ketone.

Discussion

88.	Esters of which acid are used in the perfume industry?(a) Ethanoic acid(b) Benzoic acid(c) Phthalic acid(d) Formic acidI have been asked this question in my homework.The doubt is from Uses of Carboxylic Acids topic in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct option is (b) Benzoic acid For explanation I would SAY: Esters of benzoic acids are USED in the perfumery industry. For example, ethyl BENZOATE is a component of some FRAGRANCES and artificial FLAVOURS.

Discussion

89.	Sodium acetate on heating with NaOH and CaO (3:1 mixture) gives _______(a) methane(b) ethane(c) methanol(d) ethanalThe question was posed to me during an interview.I want to ask this question from Carboxylic Acids Chemical Reactions in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct option is (a) methane To EXPLAIN: Sodium acetate UNDERGOES decarboxylation (loss of CO2) when heated with soda LIME. This is proceeded by the loss of COONa from the sodium salt and NaO from sodium hydroxide. They combine to form CH4 and Na2CO3. The hydrocarbon formed has one less carbon atom than the parent ACID.

Discussion

90.	Benzoic acid reacts with phosphorus pentachloride to give ________(a) chlorobenzene(b) benzyl chloride(c) benzoyl chloride(d) chlorobenzoic acidThis question was posed to me in an online quiz.My doubt stems from Carboxylic Acids Chemical Reactions in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right answer is (c) benzoyl CHLORIDE For EXPLANATION: The hydroxyl GROUP (OH) of benzoic acid ID EASILY replaced by chlorine atom on treatment with PCl5. This results in the formation of C6H5COCl, or benzoyl chloride.

Discussion

91.	Which of the following is used to shift the esterification reaction of carboxylic acids towards the right?(a) Using excess of carboxylic acid(b) Using excess of acid catalyst(c) Removal of water by distillation(d) Removal of ester by distillationI had been asked this question in an interview for job.My question is from Carboxylic Acids Chemical Reactions topic in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right OPTION is (c) REMOVAL of water by distillation Explanation: SINCE the esterification of CARBOXYLIC acids is a reversible reaction, it can be shifted towards the right by using excess of ALCOHOL or by the removal the water formed by distillation.

Discussion

92.	How can methyl magnesium bromide be converted to propanoic acid?(a) Jones reagent(b) KMnO4-KOH; heat(c) H3O^+; heat(d) CO2-dry ether; H3o^+This question was posed to me in examination.My question is from Methods of Carboxylic Acids Preparation in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct choice is (d) CO2-dry ether; H3o^+ To elaborate: Methyl magnesium bromide (Grignard REAGENT) on REACTION with CO2 forms an ADDITION product containing an additional C carbon atom. This is DECOMPOSED in the presence of mineral ACID to form propanoic acid.

Discussion

93.	What is the common name of the simplest dicarboxylic acid?(a) Oxalic acid(b) Malonic acid(c) Acetic acid(d) Propionic acidThis question was addressed to me in final exam.The question is from Nomenclature and Structure of Carboxyl Groups topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct option is (a) Oxalic acid Explanation: The SIMPLEST dicarboxylic acid is ethanedioc acid, which has two CARBON atoms both of which are a PART of the CARBOXYL groups. Its FORMULA is (HOOC-COOH).

Discussion

94.	What is the IUPAC name of terephthalic acid?(a) 2-Phenylethanoic acid(b) Benzene-1,2-dicarboxylic acid(c) Benzene-1,3-dicarboxylic acid(d) Benzene-1,4-dicarboxylic acidI got this question during an interview.Query is from Nomenclature and Structure of Carboxyl Groups topic in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» The correct OPTION is (d) Benzene-1,4-dicarboxylic acid The EXPLANATION: Terephthalic acid is an aromatic dicarboxylic acid with the two carboxyl groups on the opposite ends (para POSITION) of a benzene RING. 2-Phenylethanoic acid consists of only a single carboxyl group.

Discussion

95.	When an aldehyde is heated with Fehling’s solution, a reddish-brown precipitate is formed due to which compound?(a) CuS(b) AgBr(c) Cu2O(d) CdSThe question was posed to me in a job interview.My question is taken from Aldehydes and Ketones Chemical Reactions in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right choice is (c) Cu2O Explanation: Fehling’s reagent has Cu^2+ ions which OXIDISE aldehyde by ADDING an O ATOM and turning it into CORRESPONDING carboxylate ion. In this process, a reddish-brown compound is precipitated DUE to the formation of cuprous oxide.

Discussion

96.	Which of the following is used as a flavouring agent?(a) Methanal(b) Ethanal(c) Acetone(d) AcetophenoneThis question was addressed to me during a job interview.The origin of the question is Aldehydes and Ketones Physical Properties topic in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct ANSWER is (d) Acetophenone Explanation: Methanal, ethanal and acetone are LOWER carbonyl COMPOUNDS and are not much FRAGRANT to be USED as flavouring agents.

Discussion

97.	Which of the following is least reactive towards a nucleophilic attack?(a) Acetaldehyde(b) Butanone(c) Diisopropyl ketone(d) Ditert-Butyl ketoneThe question was asked during an interview.My doubt stems from Aldehydes and Ketones Chemical Reactions in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Right answer is (d) Ditert-Butyl ketone For explanation: The STEARIC EFFECTS come into consideration when comparing these compounds. Ditert-Butyl ketone has two very BULKY tert-butyl groups, one on EITHER side of the carbonyl carbon. This increases the hinderance to the INCOMING nucleophile and decreases the reactivity.

Discussion

98.	The compound 3-Bromobenzaldehyde is named as γ-Bromobenzaldehyde in the common system.(a) True(b) FalseI had been asked this question in semester exam.My enquiry is from Nomenclature and Structure of Carbonyl Groups in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» CORRECT CHOICE is (b) False Easy explanation: The prefix GAMMA- is used for substituents in a straight carbon CHAIN. For aromatic substituted compounds, the PREFIXES ortho-, meta- and para- are used. Hence, 3-Bromobenzaldehyde is named as m-Bromobenzaldehyde in the common system.

Discussion

99.	Which of the following methods cannot produce aldehydes?(a) Oxidation of primary alcohols(b) Dehydrogenation of secondary alcohols(c) Ozonolysis of alkenes(d) Hydration of ethyne with acidI had been asked this question during an online interview.My question comes from Preparation of Aldehydes and Ketones in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» Correct OPTION is (b) Dehydrogenation of secondary ALCOHOLS Easy explanation: The dehydrogenation of secondary alcohols give ketones. ALDEHYDES are OBTAINED by the dehydrogenation of PRIMARY alcohols.

Discussion

100.	What is the common name of the compound which has a CHO group attached to the sp^2 hybridised carbon of a benzene ring?(a) Benzanal(b) Benzaldehyde(c) Benzenecarbaldehyde(d) PhthaldehydeI have been asked this question in unit test.Question is from Nomenclature and Structure of Carbonyl Groups in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12
Answer» RIGHT OPTION is (b) Benzaldehyde The explanation: The IUPAC name of the simplest AROMATIC aldehyde carrying the CHO group on a benzene RING is benzenecarbaldehyde. Its common name is benzaldehyde, which is ALSO accepted by IUPAC.

Discussion

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Which of the following compounds do not contain a carbonyl group?(a) Alcohol(b) Aldehyde(c) Ketone(d) Carboxylic acidI got this question in final exam.My question is from Nomenclature and Structure of Carbonyl Groups in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Acidic hydrolysis of ethyl benzoate directly gives benzoic acid.(a) True(b) FalseI had been asked this question in an online quiz.This intriguing question comes from Methods of Carboxylic Acids Preparation topic in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Which of the following is the least soluble in water?(a) Methanal(b) Ethanal(c) Propanone(d) PentanalI got this question in my homework.My question is from Aldehydes and Ketones Physical Properties topic in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

What is the IUPAC name of CH3-CO-CH2-CH2-CH3?(a) Butan-1-one(b) Butan-2-one(c) Pentan-1-one(d) Pentan-2-oneThe question was posed to me in exam.Query is from Nomenclature and Structure of Carbonyl Groups in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Friedel-Crafts benzoylation of benzene gives ________(a) acetophenone(b) propiophenone(c) benzophenone(d) no reactionI have been asked this question in exam.My question comes from Preparation of Aldehydes and Ketones in portion Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Ammonium acetate on removal of ______ forms acetamide.(a) H2(b) NH3(c) OH^–(d) H2OThe question was posed to me in an interview for job.Asked question is from Carboxylic Acids Chemical Reactions in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

What is the common name of butanal?(a) n-Butanaldehyde(b) α-Butanaldehyde(c) n-Butyraldehyde(d) α-ButyraldehydeThe question was asked in examination.Question is from Nomenclature and Structure of Carbonyl Groups in division Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Ethanoic acid is used as vinegar in the cooking industry.(a) True(b) FalseThis question was posed to me during an online interview.I'd like to ask this question from Uses of Carboxylic Acids in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Soda lime consists of NaOH and CaO respectively, in the ratio of _______(a) 1:2(b) 2:1(c) 1:3(d) 3:1I had been asked this question in examination.The doubt is from Carboxylic Acids Chemical Reactions topic in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Esters of which acid are used in the perfume industry?(a) Ethanoic acid(b) Benzoic acid(c) Phthalic acid(d) Formic acidI have been asked this question in my homework.The doubt is from Uses of Carboxylic Acids topic in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

The compound 3-Bromobenzaldehyde is named as γ-Bromobenzaldehyde in the common system.(a) True(b) FalseI had been asked this question in semester exam.My enquiry is from Nomenclature and Structure of Carbonyl Groups in chapter Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12