chemistry MCQs - 12th class Chapter 12 Mcqs

1

What is the functional group present in both aldehydes and ketones?

A

Hydroxyl group

B

Carboxyl group

C

Carbonyl group

D

Ether linkage

2

What is the common name for methanal?

A

Acetaldehyde

B

Formaldehyde

C

Propionaldehyde

D

Butyraldehyde

3

The IUPAC name of an aldehyde is derived from the corresponding alkane by replacing the 'e' with...

A

al

B

one

C

oic acid

D

ol

4

Formalin is a mixture containing 40% formaldehyde, 52% water, and...

A

8% methyl alcohol

B

10% acetic acid

C

5% formic acid

D

8% ethyl alcohol

5

In the laboratory preparation of formaldehyde, methyl alcohol vapour is passed over a catalyst at what temperature?

A

100 °C

B

200 °C

C

300 °C

D

500 °C

6

Which catalyst is used for the industrial manufacture of formaldehyde from methanol?

A

Iron oxide-molybdenum oxide

B

Palladium chloride

C

Nickel

D

Platinised asbestos

7

Acetone is prepared by the dry distillation of which compound?

A

Calcium formate

B

Calcium acetate

C

Calcium oxalate

D

Calcium propanoate

8

The carbon atom of the carbonyl group is what type of hybridized?

A

sp

B

sp2

C

sp3

D

dsp2

9

In the carbonyl group, the oxygen atom has a partial negative charge and is considered...

A

electrophilic

B

nucleophilic

C

amphoteric

D

neutral

10

The characteristic reactions of carbonyl compounds are primarily...

A

electrophilic substitution

B

nucleophilic substitution

C

electrophilic addition

D

nucleophilic addition

11

Addition of hydrogen cyanide (HCN) to aldehydes or ketones forms...

A

cyanates

B

isocyanides

C

cyanohydrins

D

cyanamides

12

The hydrolysis of acetone cyanohydrin with an aqueous acid yields...

A

Lactic acid

B

Malic acid

C

Acetic acid

D

2-Hydroxypropanoic acid

13

Which reaction is used for the separation and purification of carbonyl compounds from non-carbonyl compounds?

A

Addition of Grignard reagent

B

Addition of sodium bisulphite

C

Aldol condensation

D

Cannizzaro's reaction

14

Aldol condensation is a reaction given by aldehydes and ketones possessing...

A

a beta-hydrogen atom

B

no hydrogen atoms

C

a gamma-hydrogen atom

D

an alpha-hydrogen atom

15

The product of an aldol condensation contains which two functional groups?

A

Aldehyde and ether

B

Alcohol and ketone

C

Aldehyde and alcohol

D

Carboxylic acid and alcohol

16

Which of the following compounds undergoes Cannizzaro's reaction?

A

Acetaldehyde

B

Propanal

C

Acetone

D

Formaldehyde

17

Cannizzaro's reaction is an example of a...

A

self oxidation-reduction reaction

B

simple addition reaction

C

elimination reaction

D

substitution reaction

18

The haloform reaction is given by acetaldehyde and...

A

all ketones

B

methyl ketones

C

ethyl ketones

D

aromatic ketones

19

The iodoform test produces a precipitate of what color?

A

Red

B

White

C

Yellow

D

Black

20

Polymerization of formaldehyde in the presence of dilute H2SO4 gives...

A

Paraldehyde

B

Metaformaldehyde

C

Bakelite

D

Formamint

21

Aldehydes react with ammonia derivatives to form compounds containing which group?

A

C=C-G

B

C-N-G

C

C=N-G

D

C-O-G

22

The reaction of acetaldehyde with hydroxylamine forms...

A

Acetaldehyde hydrazone

B

Acetaldehyde oxime

C

Ethanaloxime

D

Propanone oxime

23

Which reagent is used for the identification of aldehydes and ketones by forming yellow or orange crystalline solids?

A

Tollen's reagent

B

Fehling's solution

C

Benedict's solution

D

2,4-Dinitrophenylhydrazine

24

Reduction of aldehydes with sodium borohydride (NaBH4) yields...

A

secondary alcohols

B

tertiary alcohols

C

primary alcohols

D

carboxylic acids

25

Reduction of ketones with H2 in the presence of a Pd catalyst yields...

A

primary alcohols

B

secondary alcohols

C

tertiary alcohols

D

alkanes

26

Which of the following is a mild oxidizing agent used to test for aldehydes?

A

K2Cr2O7 / H2SO4

B

KMnO4 / H2SO4

C

Tollen's reagent

D

Conc. HNO3

27

Tollen's test with an aldehyde produces a...

A

brick-red precipitate

B

yellow precipitate

C

silver mirror

D

white precipitate

28

Which of the following does NOT give a positive Fehling's test?

A

Acetaldehyde

B

Propanal

C

Acetone

D

Butanal

29

A positive Benedict's test for an aliphatic aldehyde gives a...

A

blue solution

B

silver mirror

C

yellow solid

D

brick-red precipitate

30

The sodium nitroprusside test is used to detect which type of compound?

A

Aldehydes

B

Ketones

C

Alcohols

D

Carboxylic acids

31

Urotropine, a urinary antiseptic, is made from which compound?

A

Acetaldehyde

B

Acetone

C

Formaldehyde

D

Benzaldehyde

32

The IUPAC name for acetone is...

A

Propanal

B

Butanone

C

2-Propanone

D

Ethanal

33

In the common naming system for ketones, alkyl groups are written in which order?

A

Size order

B

Alphabetical order

C

Random order

D

Chain length order

34

Industrial preparation of acetaldehyde involves air oxidation of ethylene using which catalyst promoter?

A

Cupric chloride

B

Iron oxide

C

Silver catalyst

D

Zinc chloride

35

A base catalyst in nucleophilic addition reactions increases the nucleophilic character of the...

A

substrate

B

reagent

C

carbonyl carbon

D

product

36

What is the name of the product when propanone reacts with propanone in the presence of Ba(OH)2?

A

3-Hydroxybutanal

B

4-Hydroxy-4-methyl-2-pentanone

C

Crotonaldehyde

D

Mesityl oxide

37

In the Cannizzaro's reaction of formaldehyde, one molecule is reduced to methanol and the other is oxidized to...

A

formic acid (salt form)

B

acetic acid

C

carbon dioxide

D

carbon monoxide

38

What is the only primary alcohol that gives a positive iodoform test?

A

Methanol

B

Ethanol

C

Propanol

D

Butanol

39

Reaction of aldehydes with dry alcohol in the presence of HCl gas forms...

A

hemiacetals

B

acetals

C

ethers

D

esters

40

What is the product of the catalytic reduction of propanal?

A

2-Propanol

B

Propionic acid

C

1-Propanol

D

Acetone

41

Oxidation of butanone with a strong oxidizing agent yields acetic acid and...

A

formic acid

B

propionic acid

C

acetic acid

D

carbonic acid

42

What is the general formula for the homologous series of aldehydes and ketones?

A

CnH2n+2O

B

CnH2nO2

C

CnH2nO

D

CnHnO

43

The ketonic group is present in naturally occurring compounds like camphor and...

A

menthone

B

vanillin

C

cinnamaldehyde

D

citral

44

The reaction of acetaldehyde with semicarbazide is an example of...

A

addition-elimination reaction

B

simple addition

C

hydrolysis

D

oxidation

45

Which compound is used as a slug poison?

A

Chloral hydrate

B

Ethanol trimer

C

Paraldehyde

D

Ethanol tetramer

46

In the nomenclature of aldehydes, numbering starts from the...

A

carbon adjacent to the carbonyl group

B

end of the longest chain

C

carbonyl carbon

D

functional group attached

47

The common name Butyraldehyde corresponds to an aldehyde with how many carbon atoms?

A

2

B

3

C

4

D

5

48

Which compound is formed when acetaldehyde polymerizes in the presence of dilute H2SO4?

A

Metaformaldehyde

B

Acetal

C

Paraldehyde

D

Metaldehyde

49

The reaction of an aldehyde with a Grignard reagent, followed by hydrolysis, gives an...

A

alcohol

B

ether

C

ester

D

alkane

50

What is the role of dilute mineral acid when added to a solution of sodium cyanide in the preparation of cyanohydrin?

A

To act as a catalyst

B

To generate HCN in situ

C

To hydrolyze the product

D

To neutralize the base