CSIR NET JRF General Organic Chemistry PYQ CBT TEST

Question 1

Among the following diacids, the one that forms an anhydride fastest on heating with acetic anhydride is:
  
    (a)

HOOC
    COOH
    cis-Butenedioic acid

(b)

HOOC
    COOH
    trans-Butenedioic acid

(c)
    
    HOOC
    COOH
    Succinic acid

(d)

COOH
    COOH
    Phthalic acid

Accepted Answer

(a) Maleic acid (cis-butenedioic acid)

Answer

(b) Fumaric acid (trans-butenedioic acid)

Answer

(c) Succinic acid

Answer

(d) Phthalic acid

Question 2

The correct order of acidity of the compounds A – C is:

O

O
    A

O

O
    B

HO
    
    HO

O

O
    C

Accepted Answer

(3) C > A > B

Answer

(1) A > B > C

Answer

(2) B > C > A

Answer

(4) B > A > C

Question 3

Among the following esters, the one that undergoes acid hydrolysis fastest is:

OCOCH₃
    (1)

OCOCH₃
    
    trans-OH
    (2)

OCOCH₃
    
    cis-OH
    (3)

OCOCH₃
    
    4-OH
    (4)

Accepted Answer

(3) cis-2-Hydroxycyclohexyl acetate

Answer

(1) Cyclohexyl acetate

Answer

(2) trans-2-Hydroxycyclohexyl acetate

Answer

(4) 4-Hydroxycyclohexyl acetate

Question 4

The pair of solvents in which $	ext{PCl}_5$ does NOT ionize, is:

Accepted Answer

(3) $	ext{C}_6	ext{H}_6, 	ext{CCl}_4$

Answer

(1) $	ext{CH}_3	ext{CN}, 	ext{CH}_3	ext{NO}_2$

Answer

(2) $	ext{CH}_3	ext{CN}, 	ext{CCl}_4$

Answer

(4) $	ext{CH}_3	ext{CN}, 	ext{C}_6	ext{H}_6$

Question 5

Consider the statements about the following structures X and Y:
  
    Ph

NH
    
    CH₃
    X (Imine)

Ph

NH₂

=CH₂
    Y (Enamine)
  
(A) X and Y are resonance structures(B) X and Y are tautomers(C) Y is more basic than X(D) X is more basic than YThe correct statement(s) among the above is/are:

Accepted Answer

(4) B and C

Answer

(1) A and C

Answer

(2) C

Answer

(3) B and D

Question 6

The correct order of basicity for the following anion is:

CH₂⊖
    
    m-NO₂
    (I)

CH₂⊖
    
    p-NO₂
    (II)

CH₂⊖
    
    o-NO₂
    
    p-NO₂
    (III)

Accepted Answer

(a) I > II > III

Answer

(b) I > III > II

Answer

(c) II > I > III

Answer

(d) III > II > I

Question 7

The increasing order of pKa values of the circled hydrogen in the following compound is:

O

O
    N
    
    Me

H
    (I)

CN

H

+

H₂N
    NH₂
    BF₄⁻
    (II)

N-Me
    N⊕
    
    Me

H
    BF₄⁻
    (III)

Accepted Answer

(c) II < I < III

Answer

(a) I < II < III

Answer

(b) I < III < II

Answer

(d) II < III < I

Question 8

The decreasing order of basicity of the following compound is:

NH
    (I) Pyrrolidine

NH
    (II) Pyrrole

N
    (III) Pyridine

HN=C(NH₂)₂
    (IV) Guanidine

Accepted Answer

(c) IV > I > III > II

Answer

(a) I > II > III > IV

Answer

(b) IV > I > II > III

Answer

(d) IV > III > II > I

Question 9

The correct order of heat of hydrogenation for the following compound is:

(I)

(II)

(III)

(IV)

Accepted Answer

(b) I > III > II > IV

Answer

(a) I > II > III > IV

Answer

(c) IV > I > III > II

Answer

(d) IV > II > III > I

Question 10

Correct statement on the effect of addition of aq. HCl on the equilibrium is:
  
    HO

OH

O
    ⇌
    
    O

O
    ....Eq. A

O
    +
    ⊖CN
    ⇌

O⊖
    
    CN
    ....Eq. B

Accepted Answer

(a) Equilibrium will shift towards right in case of both A and B

Answer

(b) Equilibrium will shift towards left in case of both A and B

Answer

(c) Equilibrium will shift towards right in A and left in case of B

Answer

(d) Equilibrium will shift towards right in B and left in case of A

Question 11

The correct statements about the reaction of X and Y with NaNH₂ are:

Ph (H)
    X

Ph
    
    Ph
    
    Ph
    
    H
    Y
  
A. X reacts faster than YB. Y reacts faster than XC. X and Y behave as Lewis acidsD. X is stronger Bronsted acid than Y

Accepted Answer

(2) A and D

Answer

(1) A and C

Answer

(3) B and C

Answer

(4) B and D

Question 12

The correct order of pKa values for the compounds X, Y and Z is:
  
    NC-CH₂-CN
    X

NH
    
    O
    
    O
    Y

CH₂
    Z

Accepted Answer

(3) Z > X > Y

Answer

(1) X > Y > Z

Answer

(2) Y > Z > X

Answer

(4) Y > X > Z

Question 13

The correct order of the bond dissociation energies for the indicated C-H bond in following compounds is:

H (Allylic)
    A

H (Benzylic)
    B

H (Vinylic)
    C

Accepted Answer

(4) C > A > B

Answer

(1) C > B > A

Answer

(2) A > B > C

Answer

(3) A > C > B

Question 14

The correct order of the acidity for the following compounds is:

O
    
    O
    A (Cyclohexane-1,3-dione)

O
    
    O
    B (Cyclopentane-1,3-dione)

O
    
    O
    C (Acetylacetone)

Accepted Answer

(3) B > A > C

Answer

(1) B > C > A

Answer

(2) C > B > A

Answer

(4) C > A > B

Question 15

The correct order of pKa values for the following species is:PhNH₃⁺, (i-Pr)₂NH₂⁺, Ph₂NH₂⁺

Accepted Answer

(2) Ph₂NH₂⁺ < PhNH₃⁺ < (i-Pr)₂NH₂⁺

Answer

(1) PhNH₃⁺ < (i-Pr)₂NH₂⁺ < Ph₂NH₂⁺

Answer

(3) (i-Pr)₂NH₂⁺ < Ph₂NH₂⁺ < PhNH₃⁺

Answer

(4) PhNH₃⁺ < Ph₂NH₂⁺ < (i-Pr)₂NH₂⁺

Question 16

Among the following, the synthetic equivalent of acetyl anion is:

Accepted Answer

(d) CH₃CH₂NO₂

Answer

(a) H₃C-CHO

Answer

(b) CH₃CN

Answer

(c) 1,3-Dithiane

Question 17

The correct order of basicity for the following heterocycles is:

N
    A (Pyridine)

NH
    B (Pyrrole)

NH
    C (Pyrrolidine)

Accepted Answer

(3) C > B > A

Answer

(1) A > C > B

Answer

(2) C > A > B

Answer

(4) B > A > C

Question 18

The correct order of stability of the following carbocations is:
  
    MeO

+
    A

MeO

+
    B

MeO

+
    C

Accepted Answer

(4) C > B > A

Answer

(1) A > C > B

Answer

(2) B > C > A

Answer

(3) C > A > B

Question 19

The correct order for the rate of thermal decarboxylation of the following compounds is:

COOH
    A

N
    
    COOH
    B

N

COOH
    C

Accepted Answer

(1) C > B > A

Answer

(2) C > A > B

Answer

(3) A > C > B

Answer

(4) B > C > A

Question 20

The correct order of basicity of the following anions is:A: ⁻CH₂NO₂B: ⁻CH₂CNC: 4-NitrophenolateD: 4-Nitrobenzoate

Accepted Answer

(4) B > A > D > C

Answer

(1) B > A > C > D

Answer

(2) D > B > C > A

Answer

(3) C > D > B > A

Question 21

The synthetic equivalent of the given synthon is:

Accepted Answer

(a) t-Butyl isocyanide

Answer

(b) t-Butyl cyanide

Answer

(c) t-Butyl cyanate

Answer

(d) t-Butyl isocyanate

Question 22

The correct order of stability of the carbocations A-C is:A: Cyclopropylcarbinyl carbocationB: Allyl carbocationC: Tropylium cation

Accepted Answer

(4) C > B > A

Answer

(1) C > A > B

Answer

(2) A > C > B

Answer

(3) B > C > A

Question 23

The following carboxylic acids undergo decarboxylation upon heating. The ease of decarboxylation is in the order:A: Phenylacetic acidB: 2-Pyridylacetic acidC: 2-Nitroacetic acid

Accepted Answer

(2) C > B > A

Answer

(1) B > A > C

Answer

(3) A > C > B

Answer

(4) C > A > B

Question 24

The correct depiction of the strongest hydrogen bonded complex between benzoate anion and receptor A is:

Accepted Answer

(1) Complex 1 (Bidentate chelation of carboxylate oxygens by urea NH donors)

Answer

(2) Complex 2

Answer

(3) Complex 3

Answer

(4) Complex 4

Question 25

The correct order of basicity for following compounds is:A: 1,8-Bis(dimethylamino)naphthaleneB: N,N-DimethylanilineC: Guanidine superbase

Accepted Answer

(4) C > A > B

Answer

(1) A > B > C

Answer

(2) B > A > C

Answer

(3) C > B > A

Question 26

The correct order of reactivity of the following olefins towards ozone is:A: Alkene with electron-donating methoxy (-OMe) groupB: Simple alkyl substituted alkeneC: Conjugated alkeneD: Alkene with electron-withdrawing group

Accepted Answer

(1) A > C > B > D

Answer

(2) A > B > D > C

Answer

(3) B > C > A > D

Answer

(4) C > A > D > B

Question 27

The pKa values for the following compounds:A: DimedoneB: Diethyl malonateC: Acetylacetone

Accepted Answer

(D) B > A > C

Answer

(A) B > C > A

Answer

(B) A > B > C

Answer

(C) C > B > A

Question 28

The correct match for the bond dissociation Energies (BDE) of the C-H bonds compounds in Column I, with the values in Column II is:Column IColumn IIa. Ph-Hi. 110.9b. Allylic-Hii. 71.1c. CH≡C-Hiii. 132.0d. Alkyl-Hiv. 90.6

Accepted Answer

(d) a-iv, b-i, c-ii, d-iii

Answer

(a) a-iii, b-iv, c-i, d-ii

Answer

(b) a-i, b-iii, c-ii, d-iv

Answer

(c) a-iii, b-i, c-iv, d-ii

Question 29

The correct order for the magnitude of heats of formation of the following structural isomers is:

Accepted Answer

(d) A > C > B

Answer

(a) A > B > C

Answer

(b) B > A > C

Answer

(c) C > A > B

Question 30

The major product formed in the given reaction is:Diester + 0.95 eq. KOH (MeOH, H₂O) → Major product

Accepted Answer

(a) Mono-hydrolysis product at the less hindered ester

Answer

(b) Mono-hydrolysis product at the more hindered ester

Answer

(c) Di-acid product

Answer

(d) Transesterification product

Question 31

In the gas phase, the correct order of hydride affinity for the given carbocations is:

Accepted Answer

(4) C > A > B

Answer

(1) A > C > B

Answer

(2) B > C > A

Answer

(3) C > B > A

Question 32

In the following dithiane, the correct statement about acidity of Ha and He protons and the reason for the stability of the carbanion formed by deprotonation is:

S
    S
    
    Hₐ
    
    Hₑ

Accepted Answer

2. He is more acidic; equatorial carbanion is delocalised into the σ* orbital of C-S bond

Answer

1. Ha is more acidic; axial carbanion is delocalised into the σ* orbital of C-S bond

Answer

3. Ha is more acidic; axial carbanion is delocalised into the empty 3d orbital of sulfur

Answer

4. He is more acidic; equatorial carbanion is delocalised into the empty 3d orbital of sulphur

Question 33

The correct order for the X-H bond dissociation energies (BDE) in the following compounds is:Me₃C-H, Me₃Si-H, Me₃Sn-H

Accepted Answer

2. Me₃C-H > Me₃Si-H > Me₃Sn-H

Answer

1. Me₃Si-H > Me₃C-H > Me₃Sn-H

Answer

3. Me₃C-H > Me₃Sn-H > Me₃Si-H

Answer

4. Me₃Sn-H > Me₃C-H > Me₃Si-H

Question 34

The correct option for the pKa of following pairs of compounds is:I vs II and III vs IV

Accepted Answer

1. I > II and III > IV

Answer

2. I > II and IV > III

Answer

3. II > I and III > IV

Answer

4. II > I and IV > III

Question 35

The correct order of basicity for the following compounds is:I, II, III (Amidine and Guanidine superbases)

Accepted Answer

4. III > II > I

Answer

1. I > III > II

Answer

2. II > I > III

Answer

3. III > I > II