12th Standard Chemistry English Medium Carbonyl Compounds and carboxylic acids Reduced Syllabus Important Questions With Answer Key 2021

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Questions:

Multiple Choice Question

14 x 1 = 14

Partial reduction of acetic acid in the presence of LiAl H₄ results in the formation of ________.

(a)

ethane

(b)

ethanol

(c)

ethene

(d)

ethyne

It is a powerful acetylating agent for compounds containing -OH group and - NH group _______.

(a)

CH₃CONH₂

(b)

CH₃COOH

(c)

CH₃COCl

(d)

CH₃COOCH₃

Which compound on strong oxidation gives propionic acid?

(a)

\({ CH }_{ 3 }-\underset { \overset { | }{ OH } }{ CH } -{ CH }_{ 3 }\)

(b)

\({ CH }_{ 3 }-CO-{ CH }_{ 3 }\)

(c)

\({ CH }_{ 3 }-\overset { \underset { | }{ { CH }_{ 3 } } }{ \underset { \overset { | }{ { CH }_{ 3 } } }{ C } } -OH\)

(d)

\({ CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 }OH\)

The formation of cyanohydrin from a ketone is an example of _______.

(a)

electrophilic addition

(b)

nucleophilic addition

(c)

nucleophilic substitution

(d)

electrophilic substitution

Tincture benzoin is obtained from _______.

(a)

benzoyl chloride

(b)

benzoin

(c)

benzyl alcohol

(d)

benzoic acid

Schiff's reagent gives pink colour with _______.

(a)

acetone

(b)

acetaldehyde

(c)

ethyl alcohol

(d)

methyl acetate

Which among the carbonyl compounds cannot be prepared by Rosenmund reduction?

(a)

Ketones

(b)

Formaldehyde

(c)

Acetaldehyde

(d)

Both (a) and (b)

Cannizaro reaction is not given by _______.

(a)

(b)

(c)

CH₃CHO

(d)

HCHO

Give the common and IUPAC name of the compound HO-CH₂-\(\underset { \overset { | }{ OH } }{ CH } \)-CHO

(a)

glyceraldehyde, hydroxy prop anal

(b)

glyceraldehyde, 2, 3 - dihydroxy prop anal

(c)

crotonaldehyde, hydroxy propanal

(d)

crotonaldehyde, 2, 3 - dihydroxy propanal

10.

An alkene “A” on reaction with O₃ and Zn - H₂O gives propanone and ethanol in equimolar ratio. Addition of HCl to alkene “A” gives “B” as the major product. The structure of product “B” is ______.

(a)

\(Cl-{ CH }_{ 2 }-CH_{ 2 }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { CH_{ 3 } }{ | } }{ CH } } \)

(b)

\({ H }_{ 3 }C-{ CH }_{ 2 }-\overset { \overset { CH_{ 2 }Cl }{ | } }{ CH } -{ CH }_{ 3 }\)

(c)

\(\\ { H }_{ 3 }C-{ CH }_{ 2 }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { CL{ } }{ | } }{ C } } -{ CH }_{ 3 }\)

(d)

\({ H }_{ 3 }C-{ CH }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { Cl }{ | } }{ C } } \)

11.

In which of the following reactions new carbon – carbon bond is not formed?

(a)

Aldol condensation

(b)

Friedel craft reaction

(c)

Kolbe’s reaction

(d)

Wolf kishner reduction

12.

Which one of the following reaction is an example of disproportionation reaction.

(a)

Aldol condensation

(b)

cannizaro reaction

(c)

Benzoin condensation

(d)

none of these

13.

CH₃Br \(\overset { KCN }{ \longrightarrow } (A)\overset { { H }_{ 2 }{ O }^{ + } }{ \longrightarrow } (B)\overset { { PCl }_{ 5 } }{ \longrightarrow } \) (C) product (c) is ______.

(a)

acetylchloride

(b)

chloro acetic acid

(c)

\(\alpha\)- chlorocyano ethanoic acid

(d)

none of these

14.

Predict the product Z in the following series of reactions Ethanoic acid \(\overset { { PCI }_{ 5 } }{ \longrightarrow } X\overset { { C }_{ 6 }{ H }_{ 6 } }{ \underset { Anhydrous \ AlCI }-_{3}{ \longrightarrow } } Y\overset { 1){ CH }_{ 3 }MgBr }{ \underset { II){ H }_{ 3 }{ O }^{ + } }{ \longrightarrow } } Z.\)

(a)

(CH₃)₂ C(OH)C₆H₅

(b)

CH₃CH(OH)C₆H₅

(c)

CH₃CH(OH)CH₂- CH₃

(d)

Assertion and reason

1 x 2 = 2

15.

Assertion: p – N, N – dimethyl amino benzaldehyde undergoes benzoin condensation
Reason: The aldehydic (-CHO) group is meta directing.
Codes:
A) if both assertion and reason are true and reason is the correct explanation of assertion.
B) if both assertion and reason are true but reason is not the correct explanation of assertion.
C) assertion is true but reason is false
D) both assertion and reason are false

(a)

if both assertion and reason are true and reason is the correct explanation of assertion.

(b)

if both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

assertion is true but reason is false

(d)

both assertion and reason are false

Generic 2

10 x 2 = 20

16.

What are carboxylic acids?

17.

What is DIBAL -H? What is it used for?

18.

Arrange the following in increasing order of reactivity towards nucleophilic addition HCHO CH₃CHO and CH₃COCH₃

19.

What is formalin? Write its use.

20.

Does formaldehyde undergo aldol condensation? Justify your answer.

21.

Name one reagent used to distinguish acetaldehyde and acetone.

22.

What are the Cartesian sign conventions for a spherical mirror?

23.

Give the characteristics of image formed by a plane mirror.

24.

A hydrocarbon A (molecular formula C₈H₁₀) on ozonolysis gives B (C₄H₆O₂) only. Compound C (C₃H₅Br) on treatment with magnesium in dry ether gives (D) which on treatment with CO₂followed by acidification gives(C). Identify A, B and C.

25.

How is propanoic acid is prepared starting from
(a) an alcohol
(b) an alkylhalide
(c) an alkene

Generic 5

6 x 5 = 30

26.

Compound (A) with Molecular formula C₇H₆O does not reduce Fehling's solution. Compound (A) reacts with acetone in the presence of NaOH to give a compound (B) which is an α, β-unsaturated compound. Further (A) reacts with dimethyl aniline in the presence of cone, H₂SO₄ to give compound (C) which is a dye. Identify (A) (B) and (C). Explain the reactions.

27.

An organic compound (A) of molecular formula C₇H₈on oxidation with air and in presence of V₂O₅ to form (B) of molecular formula C₇H₆O. (B) on reduction with lithium aluminium hydride to form (C) of molecular formula C₇H₈O. Identify (A), (B) and (C) and explain the reactions.

28.

An organic compound A (C₂H₃N) on reduction with SnCI₂/HCI gives B (C₂H₄O) which reduces Tollen's reagent. Compound B on reduction with N₂H₄/C₂H₅ONa gives C (C₂H₆). Identify the compounds A, B and C. Explain the reactions involved.

29.

Explain why carboxylic acids behave as acids. Discuss briefly the effects of electron withdrawing and donating substituents on acid strength of carboxylic acids.

30.

Illustrate the reducing property of acetaldehyde with examples

31.

An alkene (A) on ozonolysis gives propanone and aldehyde (B). When (B) is oxidised (C) is obtained. (C) is treated with Br₂/P gives (D) which on hydrolysis gives (E). When propanone is treated with HCN followed by hydrolysis gives (E). Identify A, B, C, D and E.

Generic 3

11 x 3 = 33

32.

Give the IUPAC names for the following:
(i) Crotonaldehyde
(ii) Methyl n-propyl ketone
(iii) Phenyl acetaldehyde.

33.

Complete the following reactions
(i) CH₃COCI + NH₂⟶
(ii) CH₃COCI + C₂H₅OH⟶

34.

Formic acid reduces Tollen's reagent but acetic acid does not - Give reasons.

35.

Organic compound with molecular formula C₃H₆O has two isomers (A) and (B). (A) on heating with NaOH in I₂ forms a yellow precipitate while (B) does not. Identify the isomers A and B and explain the reactions.

36.

How will you convert benzaldehyde to
(I) C₆H₅COOH
(ii) C₆H_sCH₂OH
(iii) C₆HSCH₃

37.

What happens when the following compounds are treated with dilute NaOH solution in cold?
(i) propanal
(ii) (CH₃)₃C-CHO

38.

Explain the isomerism exhibited by carboxylic acids.

39.

Formaldehyde and benzaldehyde give Cannizaro reaction but acetaldehyde does not - account for this.

40.

How is acetaldehyde prepared by the ozonolysis of CH₃CH=CHCH₃?

41.

Complete the following reaction
\({ CH }_{ 3 }-{ CH }_{ 2 }-{ CH }_{ 2 }-\underset { \overset { || }{ O } }{ C } -{ CH }_{ 3 }\overset { HO-{ CH }_{ 2 }-{ CH }_{ 2 }-OH }{ \underset { { dry }{ HCl} }{ \longrightarrow } } ?\)

42.

How are the following conversions effected
(a) propanal into butanone
(b) Hex-3-yne into hexan-3-one.
(c) phenylmethanal into benzoic acid
(d) phenylmethanal into benzoin

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Answers Key:

Multiple Choice Question

14 x 1 = 14

(b)
ethanol

(d)
\({ CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 2 }OH\)

(b)
nucleophilic addition

(b)
benzoin

(b)
acetaldehyde

(d)
Both (a) and (b)

(b)
glyceraldehyde, 2, 3 - dihydroxy prop anal

10.

11.

(d)
Wolf kishner reduction

12.

(b)
cannizaro reaction

13.

14.

Assertion and reason

1 x 2 = 2

15.

B) if both assertion and reason are true but reason is not the correct explanation of assertion.

Generic 2

10 x 2 = 20

16.

(i) Organic compounds containing the carboxyl group -COOH are called carboxylic acids.
(ii) The acid may be monocarboxylic acid if it contains one -COO H group; a dicarboxylic acid if it contains two - COOH groups; a tricarboxylic acid if it contains three - COOH groups.
Eg: CH₃COOH - Acetic acid; (COOH)₂- Oxalic acid

17.

DIBAL -H is Diisobutyl aluminium hydride. Its is reducing agent.

18.

The order of reactivity of aliphatic carbonyl compounds towards the nudeophilic addition reaction is, HCHO > CH₃CHO > CH₃COCH₃

19.

(i) 40 % aqueous solution of formaldehyde is known as formalin.
(ii) It is used as a preservative for biological specimens and in leather tanning.

20.

(i) Formaldehyde does not undergo aldol condensation.
(ii) Aldol condensation reaction is the characteristic of carbonyl compounds having a hydrogen atom. So this reaction does not take place in formaldehyde.

21.

(i) Schiff's reagent is used to .distinguish acetaldehyde and acetone.
(ii) Acetaldehyde restores the original colour (red-pink) of the Schiff's reagent.
(iii) Acetone does not restore this colour.

22.

(i) The Incident light is taken from left to right (i.e. object on the left of mirror).
(ii) All the distances are measured from the pole of the mirror (pole is taken as origin).
(iii) The distances measured to the right of pole along the principal axis are taken as positive.
(iv) The distances measured to the left of pole along the principal axis are taken as negative.
(v) Heights measured in the upward perpendicular direction to the principal axis are taken as positive.
(vi) Heights measured in the downward perpendicular direction to the principal axis, are taken as negative.

23.

(i) The image formed by a plane mirror is virtual, erect, and laterally inverted.
(ii) The size of the image is equal to the size of the object.
(iii The image distance far behind the mirror is equal to the object distance in front of it.
(iv) If an object is placed between two plane mirrors inclined at an angle e, then the number of images n formed is as,
\(n=\left( \cfrac { 360 }{ \theta } -1 \right) \)

24.

The compound with molecular formula C₈H₁₀

Compound (C) with molecular formula C₃H_SBr is

25.

An alcohol:

An alkylhalide:

An alkene:

Generic 5

6 x 5 = 30

26.

(i) Compound (A) does not reduce Fehling's solution, so it is benzaldehyde.
(ii) Benzaldehyde (A) reacts with acetone in the presence of NaOH to give on a, p unsaturated compound (B).
\(\\ \\ \\ \underset { (A) }{ { C }_{ 6 }{ H }_{ 5 }CHO } +{ CH }_{ 3 }-{ COCH }_{ 3 }\overset { NaoH }{ \longrightarrow } \underset { (B) }{ { C }_{ 6 }{ H }_{ 5 } } -\underset { Acetone }{ CH=CH-{ COCH }_{ 3 } } \)
(iii) (A) reacts with dimethyl aniline in the presence of conc. H₂SO₄ to give compound (C).

Compound	Compound Name	Formula
A	Benzaldehyde	C₆H₅CHO
B	Benzal acetone	C₆H₅CH = CH-COCH₃
C	Triphenyl methane dye

27.

(i) (A) on oxidation with air and V₂O₅ gives (B).
\(\underset{(A)}{{ C }_{ 6 }{ H }_{ 5 }{ CH }_{ 3 }}\overset { \left( O \right) }{ \underset { { V }_{ 2 }{ O }_{ 5 } }{ \longrightarrow } } \underset{(B)}{{ C }_{ 6 }{ H }_{ 5 }CHO}\)
(ii) (B) on reduction with LiAIH₄gives C.
\({ C }_{ 6 }{ H }_{ 5 }CH\overset { \left[ H \right] }{ \underset { LiA/{ H }_{ 4 } }{ \longrightarrow } } \underset{(C)}{{ C }_{ 6 }{ H }_{ 5 }CHO}\)

Compound	Compound Name	Formula
A	Toluene	C₆H₅CH₃
B	Benzaldehyde	C₆H₅CHO
C	Benzylalcohol	C₆H₅CH₂OH

28.

(i) An organic compound A (C₂H₃N) on reduction with SnCl₂/HCI gives B (C₂H₄O) which reduces Tollens reagent.
\({ CH }_{ 3 }-C\overset { | }{ \underset { \underset { H-H\\ \quad (A) }{ | } }{ = } } N\overset { sn{ Cl }_{ 2 } }{ \underset { HCl }{ \longrightarrow } } { CH }_{ 3 }CH=NH-HCl\overset { Hydrolysis }{ \longrightarrow }\underset{(B)} {{ CH }_{ 3 }CHO}+{ NH }_{ 4 }Cl\)
(ii) Compound B on reduction with N₂H₄/C₂H₅ONa gives C (C₂H₆).

Compound	Compound Name	Formula
A	Methyl cyanide	CH₃-CN
B	Acetaldehyde	CH₃CHO
C	Ethane	C₂H₆

29.

Acidic nature of acids:
(i) Acid molecule ionises to produce H⁺ ions in solution.

(ii) The carboxylate anion is stabilised by resonance.

Hence the cleavage of -COOH bond to release H⁺is favoured, thereby making it to behave as acids.
(iii) Any factor that weakens the -COOH bond will facilitate the cleavage to release H⁺ more easily. The degree of ionisation is increased and acid becomes relatively a stronger acid.
(iv) When the following acids are compared
Their strength varies as the above order.
(v) Methyl group is a + I group (electron pair repelling group). Acid strength decreases: with increasing number of electron repelling substituent attached to the α- carbon atom.

The +1 effect is felt in increasing the strength of the -OH bond and the cleavage to form H+ becomes difficult. Hence they are weaker acid than formic acid (HCOOH) which does not have + I methyl group.
(vi) Acid strength increases with increase in electronegativity of substituents

This effect weakness the -O- H bond there by facilitating the removal of H⁺ from -OH group. This acid becomes stronger than formic acid.

30.

\(\underset { Acetaldehyde }{ { CH }_{ 3 }-\underset { \overset { || }{ O } }{ C } -H+4(H) } \overset { { NH }_{ 2 }{ NH }_{ 2 } }{ \underset { { C }_{ 2 }{ H }_{ 5 }ONa }{ \longrightarrow } } \underset { Ethane }{ { CH }_{ 3 }-{ CH }_{ 3 }+{ H }_{ 2 }O+{ N }_{ 2 } } \)
(i) Clemmensen reduction: Aldehydes and Ketones when heated with zinc amalgam and concentrated hydrochloric acid gives hydrocarbons.
Example:
\(\underset { Acetald4ehyde }{ { CH }_{ 3 }-\underset { \overset { || }{ O } }{ C } -{ H }^{ + }4(H) } \overset { Zn^{ - }Hg }{ \underset { Conc.HCl }{ \longrightarrow } } \underset {Ethane}{{ CH }_{ 3 }-{ CH }_{ 3 }\pm { H }_{ 2 }O}\)
\(\underset { Acetone }{ { CH }_{ 3 }-\underset { \overset { || }{ O } }{ C } -{ CH }_{ 3 }+4\left( H \right) } \overset { { Zn }^{ - }Hg }{ \underset { Conc.HCl }{ \longrightarrow } } { CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 3 }+{ H }_{ 2 }O\)
(ii) Wolff-Kishner Reduction: Aldehydes and Ketones when heated with hydrazine (NH₂NH₂) and sodium ethoxide, hydrocarbons are formed Hydrazine acts as a reducing agent and sodium ethoxide as a catalyst.
Example :
\(\underset { Acetaldehyde }{ { CH }_{ 3 }-\underset { \overset { || }{ O } }{ C } -H+4(H) } \overset { { NH }_{ 2 }{ NH }_{ 2 } }{ \underset { { C }_{ 2 }{ H }_{ 5 }ONa }{ \longrightarrow } } \underset { Ethane }{ { CH }_{ 3 }-{ CH }_{ 3 }+{ H }_{ 2 }O+{ N }_{ 2 } } \)
\(\underset { Acetone }{ { CH }_{ 3 }-\underset { \overset { || }{ O } }{ C } -{ CH }_{ 3 }+4(H) } \overset { { NH }_{ 2 }{ NH }_{ 2 } }{ \underset { { C }_{ 2 }{ H }_{ 5 }ONa }{ \longrightarrow } } { CH }_{ 3 }{ CH }_{ 2 }{ CH }_{ 3 }+{ H }_{ 2 }O+{ N }_{ 2 }\)
Aldehyde (or) ketones is first converted to its hydrazone which on heating with strong base gives hydrocarbons.
(iii) Reduction to pinacols: Ketones, on reduction with magnesium amalgam and water, are reduced to symmetrical diols known as pinacol.

31.

Generic 3

11 x 3 = 33

32.

S.No.	Formula	Common name	IUPAC name
i.	CH₃-CH=CH-CHO	Crotonaldehyde	2-butenal
ii.	\(CH_{ 3 }-\underset { \overset { \|\| }{ O } }{ C } -{ CH }_{ 2 }-{ CH }_{ 2 }-{ CH }_{ 3 }\)	Methyl n-propyl ketone	2-pentanone
iii.	C₆H_sCH₂CHO	Phenyl acetaldehyde	Phenyl ethanal

33.

(i) Reaction with Ammonia (Ammonolysis) gives acid amides :
\(\underset { Acetyl\quad chloride }{ { CH }_{ 3 }-\overset { \underset { || }{ O } }{ C } - } \boxed { Cl+H } \underset { Ammonia }{ -{ NH }_{ 2 } } \longrightarrow \underset { Acetamide }{ { CH }_{ 3 }-\overset { \underset { || }{ O } }{ C } -{ NH }_{ 2 } } +HCl\)
(ii) Reaction with Alcohols (Alcoholysis) gives esters

34.

(i) Formic acid (HCOOH) is unique because it contains both an aldehyde group and carboxyl group also.
(ii) Hence it can act as a reducing agent. It reduces Fehling's solution Tollen's reagent and decolourises pink coloured KMnO₄ solution.
(iii) Whereas in acetic acid, there is no aldehyde group and it cannot act as reducing agent.
(iv) Formic acid reduces ammoniacal silver nitrate solution (Tollen's reagent) to metallic silver
HCOOH + Ag₂O⟶ H₂O + CO₂ + 2Ag↓ (metallic silver)
(v) Formic acid reduces Fehling's solution. It reduces blue coloured cupric ions to red coloured cuprous ions.
\(HCOO^{ - }+\underset { (blue) }{ 2{ Cu }^{ 2+ } } +5{ OH }^{ - }\longrightarrow { CO }_{ 3 }^{ 2- }+\underset { (red) }{ { Cu }_{ 2 }O } +3{ H }_{ 2 }O\)

35.

Two possible isomers of C₃H₆O are
\(\underset { \overset { (A) }{ Acetone } }{ { CH }_{ 3 }CO{ CH }_{ 3 } } \quad \underset { \overset { (B) }{ Propanal } }{ { CH }_{ 3 }{ CH }_{ 2 }CHO } \)
\(\\ \underset { \quad \quad (A)\\ Proponal }{ { CH }_{ 3 }CO{ CH }_{ 3 } } \overset { { I }_{ 2 }/NaOH\Delta }{ \underset { Iodo\ form\ \\ reaction }{ \longrightarrow } } \underset { Sodium\\ acetate }{ { CH }_{ 3 }COONa } +\underset { Iodoform\\ Yellow\ ppt }{ { CHI }_{ 3 } } \)
\(\underset { \quad \quad \quad (B)\\ Propanal }{ { CH }_{ 3 }{ CH }_{ 2 }CHO } \overset { { I }_{ 2 }/NaOH }{ \underset { \Delta }{ \longrightarrow } } No\quad ppt\quad of\quad { CHI }_{ 3 }\)
Acetone answers Iodo form test whereas proponal does not.

36.

(i) It is oxidised to benzoic acid by alkaline permanganate.
\({ C }_{ 6 }{ H }_{ 5 }CHO\overset { [O] }{ \longrightarrow } { C }_{ 6 }{ H }_{ 5 }COOH\)
(ii) It is reduced to benzyl alcohol by NaBH₄ or LiAlH₄
\({ C }_{ 6 }{ H }_{ 5 }CHO\overset { \left[ { H }^{ - } \right] }{ \longrightarrow } { C }_{ 6 }{ H }_{ 5 }{ CH }_{ 2 }OH\)
(iii) It can be reduced to toluene by Clemmenson or Wolff Kishner procedure.
\({ C }_{ 6 }{ H }_{ 5 }CHO\overset { Zn/Hg/HCl }{ \underset { \overset { or }{ { N }_{ 2 }{ H }_{ 4 }/KoH } }{ \longrightarrow } } { C }_{ 6 }{ H }_{ 5 }{ CH }_{ 3 }\)

37.

(i) \(\underset { Propanal }{ { 2CH }_{ 3 }-{ CH }_{ 2 }-CHO } \overset { Dil\quad NaOH }{ \underset { \quad Aldol\\ Condensation }{ \longrightarrow } } \underset { 3-hydroxy-2-methyl \ pentanal }{ { CH }_{ 3 }-{ CH }_{ 2 }-\underset { \overset { | }{ OH } }{ CH } -\underset { \overset { | }{ { CH }_{ 3 } } }{ CH } -CHO } \)
(ii) (CH₃)C-CHO:
\({ CH }_{ 3 }-\overset { \underset { | }{ { CH }_{ 3 } } }{ \underset { \overset { | }{ { CH }_{ 3 } } }{ C } - } CHO\overset { dil.NaOH }{ \underset { Cannizzao\\ reaction }{ \longrightarrow } } \underset { 2,2diemthy-l-propanol }{ { CH }_{ 3 }-\overset { \underset { | }{ { CH }_{ 3 } } }{ \underset { \overset { | }{ { CH }_{ 3 } } }{ C } } -{ CH }_{ 2 }OH+ } \underset { 2,2-dimethyl \ sodium \ propionate }{ CH_{ 3 }-\overset { \underset { | }{ { CH }_{ 3 } } }{ \underset { \overset { | }{ { CH }_{ 3 } } }{ C } } -COONa } \)

38.

(i) Chain isomerism: This arises due to the difference in the carbon chain of alkyl group attached to carboxyl group. C₅H₁₀O₂.
\({ CH }_{ 3 }-\underset { Pentanoic\ acid }{ { CH }_{ 2 }-{ CH }_{ 2 }-{ CH }_{ 2 } } -COOH\quad \underset { 3-mrthyl\ butanoic\ acid }{ { CH }_{ 3 }-\overset { \underset { | }{ { CH }_{ 3 } } }{ CH } -{ CH }_{ 2 }-COOH } \)
(ii) Functional isomerism: Carboxylic acids are functional isomers of ester . C₃H₆O₂
\(\underset { Propanic \ acid }{ { CH }_{ 3 }-{ CH }_{ 2 }-COOH } \) and \(\underset { Methyl\ acetate }{ { CH }_{ 3 }COO{ H }_{ 5 } } \) \(\underset { Ethyl\ formate }{ HCOO{ C }_{ 2 }{ H }_{ 5 } } \)

39.

(i) Cannizzaro reaction is a redox reaction which takes place only in aldehydes which do not have α- hydrogen atom.
(ii) Formaldehyde (HCHO) and benzaldehyde (C₆H₅CHO) do not have a-hydrogen atom and so they undergo Cannizzaro reaction.
(iii) But acetaldehyde CH₃CHO contains 3 α-H atoms and it does not undergo Cannizzaro reaction.

40.

Ozone forms addition product with olefin called I ozonide, which on reductive cleavage gives aldehyde.

41.

2- Pentanone.

42.

Propanal into butanone:

(b) Hex-3-yne into hexan-3-one.
Hydration of alkynes in 42% sulphuric acid containg H₂SO₄ as catalyst
\(\underset {Hex-3-yne}{\mathrm{CH}_{3}-\mathrm{CH}_{2}}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}_{2}-\mathrm{CH}_{3} \frac{\mathrm{HgSO}_{4}}{\mathrm{H}_{2} \mathrm{SO}_{4} / \mathrm{H}_{2} \mathrm{O}} \)

(c) phenylmethanal into benzoic acid

(d) phenylmethanal into benzoin