Aldehydes, Ketones and Carboxylic Acids Test 8

Result

Aldehydes, Ketones and Carboxylic Acids Test 8

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

Only One Option Correct Type
Direction (Q. Nos. 1-14) This section contains 14 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
Q.
In hexane-2,4-dione, how many different mono-enols are possible?

A
2

B
3

C
4

D
7

Solution
Question 2
1 / -0

What is the correct order of equilibrium enol content of the following compounds?
I. CH₃COCH₃
II. CH₃COCH₂COOC₂H₅
III. CH₃COCH₂COCH₃
IV. CH₃COCH₂COH

A
I > II > III > IV

B
I > IV > III > II

C
IV > II > III > I

D
III > IV > II > I

Solution

A 1,3-diketo compound forms more stable enol than a monocarbonyls. Also ester group forms less stable enol than carbonyls. Hence, III, a 1 , 3-diketo ne form s highest enol content while I (monocarbonyl) forms least enol content at equilibrium.
Question 3
1 / -0

In which of the following compounds, enol form exist?

A
C₆H₅COCH₃

B
C₆H₅CHO

C

D
Both (a) and (c)

Solution

Both option (a) and option (c) forms enol but option (b) does not form enol.
Question 4
1 / -0

Among the following compounds, one that will not show keto-enol tautomerism is

A

B

C

D

Solution

sp² hybridisation is very less stable at bridgehead carbon of a bicyclic compound.
Question 5
1 / -0

Arrange the following in the increasing order of hydrate content at equilibrium in aqueous solution
I. H₂CO

III. C₆H₅CHO

A
I < II < III < IV

B
IV < III < II < I

C
III < IV < II < I

D
Ill < IV < I < II

Solution

Due to negligible steric hindrance, form aldehyde form s large hydrate content at equilibrium. Also electron withdrawing group in (IV) increases hydrate content compared to III.
Question 6
1 / -0

For which of the following equilibrium, K_c< 1 ?

A

B

C

D

Solution

In the absence of any special stability factor, a hydrate of ketone is highly unstable.
Question 7
1 / -0

Arrange the following in the increasing order of stability of their most stable enol.

A
I < II < III < IV

B
IV < III < II < I

C
II < I < IV < III

D
III < IV < II < I

Solution

Diketo (I) forms highest enol content due to stabilisation of enol by intermolecular H-bonding. Electron donating resonance effect by ester group slightly decreases enol content.
Question 8
1 / -0

Which of the following observation does not establish the existence of keto-enol tautomerism in acetone?

A
When treated with DCI in D₂O, hexadeuterated acetone is recovered

B
When treated with D₂O/NaOD, hexadeuterated acetone is recovered

C
When treated with dil. H₂SO₄ in H₂O¹⁸, is obtained

D
All of the above establishes keto-enol tautomerism

Solution

The above exchange occur due to existence of hydrate equilibrium.
Question 9
1 / -0

Hemiacetals are usually unstable whereas acetals are stable. Which has the most stable hemiacetal?

A

B

C

D

Solution

If a hemiacetal is five or six membered cyclic, they are stable.
Question 10
1 / -0

Which form s most stable acetal in the given condition?

A

B

C

D

Solution
Question 11
1 / -0

Consider the following reaction,
Q.
The appropriatensequence of reagent that can best bring about the above conversion is

A
(i) CH₃MgBr (1.0 equiv.) (ii) Conc. H₂SO₄/ Heat

B
(i) CH₃Li(1.0 equiv.)(ii)Conc. H₂SO₄/Heat

C
(i) C₂H₅OH (2.0 equiv.); H⁺ (ii) CH₃MgBr (iii) Conc. H₂SO₄/Heat

D
(i) HOCH₂CH₂OH; H⁺ (ii) CH₃MgBr (iii) Conc. H₂SO₄/Heat (iv) H₃O⁺/H₂O

Solution
Question 12
1 / -0

What is the major product in the following reaction?

A

B

C

D

Solution

Acetal is form ed by cyclisation
Question 13
1 / -0

Which of the following has greater enol content than keto counter part?

A
C₆H₅—CH₂CHO

B

C

D

Solution

It is 1, 3-dik eto compound, forms stable enol.
Question 14
1 / -0

Arrange the following in the increasing order of acidic strength
I. H₂CO
II. CH₃CHO
III. C₆H₅CH₂CHO

A
I < II < III < IV

B
IV < III < II < I

C
III < IV < II < I

D
III < IV < I < II

Solution

IV is most acidic as its conjugate base is resonance stabilised by two carbonyl groups, followed by III whose conjugate base is resonance stabilised by a carbonyl group and phenyi ring.