Aldehydes Ketones and Carboxylic Acids Test

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Aldehydes Ketones and Carboxylic Acids Test - 28

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Weekly Quiz Competition

Question 1
1 / -0

Acetic acid is present in vinegar. Curd contains ______ .

A
lactic acid

B
tartaric acid

C
picric acid

D
None of the above

Solution

Lactic acid is present in curd. The increased acidity causes the milk proteins to tangle into curds.
Question 2
1 / -0

_______ is/are used in the manufacture of bakelite polymer.

A
Propyl alcohol

B
Phenol

C
Formaldehyde

D
both B and C

Solution

Phenol and formaldehyde are used in the manufacture of Bakelite polymer.
Question 3
1 / -0

Formaldehyde is used :

A
for preserving biological specimens

B
for the preparation of urotropine

C
in the manufacture of bakelite

D
all of these

Solution

Formaldehyde is used for preserving specimens for the preparation of Urotropine and in manufacture of Bakelite.
Question 4
1 / -0

How does acetaldehyde react with the following reagents ?

A
Dilute aqueous caustic soda

B
Hydrazine

C
Ammoniacal silver nitrate

D
Phosphorus pentachloride.

Solution

(a) Aldehydes and ketones having at least one $$\alpha$$-hydrogen undergo a reaction in the presence of dilute aqueous caustic soda as catalyst to form $$\alpha$$-hydroxy aldehydes (aldol). This is known as aldol reaction.
$$\underset{\displaystyle Acetaldehyde}{2CH_3-CHO}\overset{Dil. NaOH}{\rightarrow}\underset{\displaystyle 3-hydroxybutanal}{CH_3-\underset{\underset{\displaystyle OH}{|}}{C}H-CH_2-CHO}\overset{H^+}{\underset{\Delta}{\rightarrow}}\underset{\displaystyle But-2-enal}{CH_3-CH=CH-CHO}$$
(b) The carbonyl group of acetaldehyde reacts with hydrazine to produce a hydrazone in which the carbon is double bonded to nitrogen.
(c) When acetaldehyde is warmed with freshly prepared ammoniacal silver nitrate solution, a bright silver mirror is produced. The aldehyde gets oxidized to acetate ion and silver ion is reduced to metallic silver.
$$CH_3CHO+2[Ag(NH_3)_2]^-+3OH^-\rightarrow \underset{Acetate ion}{CH_3COO^-}+\underset{(silver mirror)}{2Ag}\downarrow+2H_2O+4NH_3$$
(d) Acetaldehyde on reaction with Phosphorus pentachloride, gives gem-dichloride.
$$\underset{\displaystyle Acetaldehyde}{CH_3CHO}+\underset{\underset{\displaystyle pentachloride}{\displaystyle Phosphorus}}{PCl_5}\rightarrow \underset{\displaystyle gem-dichloride}{CH_3CHCl_2}+POCl_3$$.
Question 5
1 / -0

Out of aldehyde and ketones, which is more reactive towards nucleophilic addition?

A
Aldehyde

B
Ketone

C
Equally reactive

D
Cannot be predicted

Solution

Aldehydes are usually more reactive toward nucleophilic substitutions than ketones because of both steric and electronic effects.

In aldehydes, the relatively small hydrogen atom is attached to one side of the carbonyl group, while a larger $$R$$ group is affixed to the other side. But in ketone, two larger $$R$$ groups are attached to both sides.

Sterically, the presence of two relatively large substituents in ketones hinders the approach of nucleophile to carbonyl carbon than in aldehydes having only one such substituent.

Electronically, two alkyl groups reduce the electrophilicity of the carbonyl carbon more effectively in ketones than in aldehyde.

Hence Aldehydes are more reactive toward nucleophilic addition reactions than Ketones.
Question 6
1 / -0

Which of the following is used for preserving biological specimens?

A
Formaldehyde

B
Ether

C
Ethyl alcohol

D
None of these

Solution

Formaldehyde ($$HCHO$$) in the form of formalin (40% solution of formaldehyde) is used for preserving biological specimens.
Question 7
1 / -0

Which acid is used in medicine for the treatment of gout?

A
Hydrochloric acid

B
Methanoic acid

C
Ethanoic acid

D
None of these

Solution

Methanoic acid is used in treatment of Gout.
Question 8
1 / -0

Formalin is _______ % solution of formaldehyde in water

A
10

B
20

C
40

D
60

Solution

Formalin is $$40$$% solution of formaldehyde in water.
Formalin means $$40$$% formaldehyde.
Question 9
1 / -0

Benzaldehyde is used:

A
as a flavouring agent for food

B
in the manufacture of triphenylmethane dyes like malachite green

C
as a starting material for the preparation of cinnamic acid

D
all of these

Solution

Benzaldehyde is used as flavoring agent, manufacture of dyes like triphenylmethane dyes and also as starting material for the preparation of cinnamic acid.
Question 10
1 / -0

________ is used in the preparation of chloroform, sulphonal, cordite etc.

A
formalin

B
ethyl alcohol

C
acetone

D
none of these

Solution

Preparation of chloroform from acetone is:
$$CaOCl_2+H_2O\longrightarrow Ca(OH)_2+Cl_2$$
$$CH_3COCH_3+3Cl_2\longrightarrow CCl_3COCH_3+3HCl$$
$$2CCl_3COCH_3+Ca(OH)_2\longrightarrow 2CHCl_3+(CH_3COO)_2Ca$$
Preparation of sulphonal from ketone is shown in IMAGE $$01$$
Preparation of cordite is shown in Image $$02$$
Cordite is a propellant which is addition product of ketone.
Hence, above all are prepared from acetone.

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Aldehydes Ketones and Carboxylic Acids Test - 28

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Aldehydes Ketones and Carboxylic Acids Test - 28

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SHARING IS CARING

Question 1

lactic acid

tartaric acid

picric acid

None of the above

Solution

Question 2

Propyl alcohol

Phenol

Formaldehyde

both B and C

Solution

Question 3

for preserving biological specimens

for the preparation of urotropine

in the manufacture of bakelite

all of these

Solution

Question 4

Dilute aqueous caustic soda

Hydrazine

Ammoniacal silver nitrate

Phosphorus pentachloride.

Solution

Question 5

Aldehyde

Ketone

Equally reactive

Cannot be predicted

Solution

Question 6

Formaldehyde

Ether

Ethyl alcohol

None of these

Solution

Question 7

Hydrochloric acid

Methanoic acid

Ethanoic acid

None of these

Solution

Question 8

10

20

40

60

Solution

Question 9

as a flavouring agent for food

in the manufacture of triphenylmethane dyes like malachite green

as a starting material for the preparation of cinnamic acid

all of these

Solution

Question 10

formalin

ethyl alcohol

acetone

none of these

Solution

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