IIT JEE Super Course in Chemistry: Organic Chemistry

Trishna Knowledge Systems

Chapter 1

Basic Organic of Chemistry - all with Video Answers

Educators

Chapter Questions

Problem 1

Give the IUPAC name for $\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}_{2}-\mathrm{CH}_{3}$

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Problem 2

Four pairs of structures are given below. How many of these pairs are resonance pairs?
(a) and $: \stackrel{\Theta}{N}=\stackrel{+}{N}=\stackrel{\Theta}{N}$ :
(b) and
(d) $\mathrm{H}_{2} \mathrm{C}-\mathrm{CH}=\mathrm{CH}-\mathrm{C} \mathrm{H}_{2}$ and $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_{2}$
(d) $\mathrm{H}-\mathrm{C} \equiv^{+} \mathrm{N}-\ddot{\mathrm{O}}^{\circ}$ and $\mathrm{H}-\mathrm{C}=\mathrm{N}^{+}=\ddot{\mathrm{O}}$

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Problem 3

Draw curved arrows to convert the first structure in each set to the other.

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Problem 4

Account for the fact that carboxylic acids are more acidic compared to an alcohol.

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Problem 5

Account for the indicated order of base strength among the compounds shown. $\mathrm{CH}_{3} \mathrm{NH}_{2}>\mathrm{NH}_{3}>\mathrm{NF}_{3}$

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Problem 6

Write the enol forms and identify the more stable form in each of the following compounds.
(i) 1-phenyl-2-butanone
(ii) methyl isopropyl ketone

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Problem 7

Carbon - oxygen bond lengths in formic acid are $1.23 \mathrm{~A}^{\circ}$ and $1.36 \mathrm{~A}^{\circ}$ respectively. $\mathrm{H}-\mathrm{C}_{1} \quad$ However, both the carbon -oxygen bonds have the same value in the formate ion Rationalize.

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Problem 8

How are the following compounds related?

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Problem 9

Account for the fact that $\mathrm{CHCl}$, is more acidic than $\mathrm{CHF}_{3} .$

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Problem 10

Optically active 2 -iodobutane on treatment with NaI, loses its optical activity. Explain why.

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Problem 11

IUPAC name of the compound is
(a) 4 -Ethyl-3-methyl hex-1-en-2-ol
(b) 3 -Ethyl-4-methyl hex- 5 -en- 2 -ol
(c) 3-Methyl-4-ethyl hex-1-en-2-ol
(d) 3-Ethyl-4-methyl-2-hydroxy hex-5-ene.

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Problem 12

(a) diastereomers
(b) constitutional isomers
(c) enantiomers
(d) two different representations of the same compound

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Problem 13

Phenol is more acidic than ethyl alcohol because
(a) phenol is soluble in $\mathrm{NaOH}$
(b) the phenoxide ion is resonance stabilized
(c) ethyl alcohol is not soluble in $\mathrm{NaOH}$
(d) the conjugate base of phenol is strong

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Problem 14

The most stable carbocation among the following is

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Problem 15

The relationship between
(a) they are enantiomers
(b) they are anomers
(c) they are meso compounds
(d) they are diasteromers

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Problem 16

Directions: Each question contains Statement-1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement-1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1
If a triple bond is present, along with a double bond and another functional group, the order of priority will be Functional group $>$ double bond $>$ triple bond.
and
Statement 2
The compound is named as 4-chloro-3-nitrobutanal.

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Problem 17

Directions: Each question contains Statement-1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement-1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 Between $\mathrm{CCl}_{3}-\mathrm{COOH}$ and oxalic acid, the former is a stronger acid. and
Statement 2 Electron withdrawing groups decrease the acid strength and increase the base strength.

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Problem 18

Directions: Each question contains Statement-1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement-1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 All the carbon atoms are $\mathrm{sp}^{2}$ hybridized in allene $\mathrm{H}_{2} \mathrm{C}=\mathrm{C}=\mathrm{CH}_{2}$. and
Statement 2
The two $\mathrm{H}$ atoms on the first carbon and two hydrogen atoms on the third carbon lie in perpendicular planes in allene.

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Problem 19

Directions: Each question contains Statement-1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement-1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 The energy of the resonance hybrid is always lower than that of any of the contributing resonance structures. and
Statement 2
Greater the number of contributing structures with similar energies greater is the stabilization and lower is the energy of the hybrid.

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Problem 20

Directions: Each question contains Statement-1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement-1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 A carbocation can rearrange to form a more stable carbocation or will combine with a nucleophile to form a stable compound or can eliminate a proton to form an olefin. and
Statement 2 The order of stabilities of carbocation and free radicals is the same.

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Problem 21

Conformational isomers are structures obtained by rotation around single bonds. Conformational isomers are easily interconvertible as the energy differences are very small between the various structures.
The conformation of cyclohexane which is most stable is
(a) boat
(b) twist boat
(c) chair
(d) planar

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Problem 22

Conformational isomers are structures obtained by rotation around single bonds. Conformational isomers are easily interconvertible as the energy differences are very small between the various structures.
The compound which can have conformations among the following is
(a) $\mathrm{CH}_{3} \mathrm{Cl}$
(b) $\mathrm{CH}_{2}=\mathrm{CH}_{2}$
(c) $\mathrm{CH}_{2} \mathrm{Cl}-\mathrm{CH}_{2} \mathrm{Cl}$
(d)

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Problem 23

Conformational isomers are structures obtained by rotation around single bonds. Conformational isomers are easily interconvertible as the energy differences are very small between the various structures.
Consider the structure of $\mathrm{n}$ -butane given below Which of the following statements is correct?
(a) The structure given above is the Gauche conformation.
(b) The dihedral angle between the two methyl groups is zero.
(c) A staggered conformation has a higher energy compared to an eclipsed form.
(d) The energy difference between the various conformers is so great that the various forms can be isolated easily.

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Problem 24

Tautomerism is a kind of isomerism where the two isomers are inter convertible by a 1,3 shift of a proton. The isomers exists as an equilibrium mixture of two forms viz., keto and enol. Generally either a keto or an enol form predominates.
A compound that cannot exhibit tautomerism is

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Problem 25

Tautomerism is a kind of isomerism where the two isomers are inter convertible by a 1,3 shift of a proton. The isomers exists as an equilibrium mixture of two forms viz., keto and enol. Generally either a keto or an enol form predominates.
Identify the statement/equation which is not correct among the following.

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Problem 26

Tautomerism is a kind of isomerism where the two isomers are inter convertible by a 1,3 shift of a proton. The isomers exists as an equilibrium mixture of two forms viz., keto and enol. Generally either a keto or an enol form predominates.
A pair of structures which are not tautomeric pairs among the following is

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Problem 27

The compounds which have only primary and tertiary carbon are
(a) 2 -methylbutane
(b) 2,3 -dimethylbutane
(c) 2-chloro-2-methylpropane
(d) 2,2 -dimethylpropane

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Problem 28

Which of the following are correct statements?
(a) $\mathrm{BF}_{3}$ and are: $\mathrm{CCl}_{2}$ electrophiles.
(b) Dimethylsulphoxide and dimethyl formamide (DMF) are aprotic solvents.
(c) In butadiene $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_{2}$ all the three $\mathrm{C}-\mathrm{C}$ bond lengths are equal.
(d) $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{Cl}$ has low reactivity because chlorine is attached to an $\mathrm{sp}^{2}$ carbon.

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Problem 29

Identify the pair or pairs which are correctly represented.
(a) $\quad$ and $\quad$ are enantiomers
(b) and $\quad$ are two representations of the same compound
\begin{tabular}{l|l|l} (c) & and & are erythro and threo forms \end{tabular}
(d) $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_{2}$ and
are ring chain isomers.

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Problem 30

Match the elements of Column I to elements of Column II. There can be single or multiple matches.
Column I
(a) $\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}{ }^{+}$
(b) Buta- 1,3 -diene
(c) $\mathrm{CH}_{3}-\dot{\mathrm{C}} \mathrm{H}_{2}$
(d) Benzene.
Column II
(p) Conjugation
(q) Hyperconjugation
(r) $\mathrm{sp}^{2}$ hybridized carbon
(s) Rearrangement

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Problem 31

The IUPAC name of $\mathrm{CH}_{3}-\mathrm{CO}-\mathrm{CHCl}-\mathrm{CH}_{2}-\mathrm{COOH}$ is
(a) 3-Chloro-4-oxopentanoic acid
(b) 4-Oxo-3-Chloropentanoic acid
(c) 2-Oxo-3-Chloropentanoic acid
(d) 1 -Carboxy-3-Chloro-4-ketobutane

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Problem 32

$\mathrm{Cl} \mathrm{CH}_{2}-\mathrm{CHCl}-\mathrm{CH}=\mathrm{CH}_{2}$ is known by IUPAC nomenclature as
(a) $1,2-$ dichloro but $-3$ -ene
(b) $3,4-$ dichloro but-2-ene
(c) $3,4-$ dichloro but-1-ene
(d) 1,2 -dichloro butene-3

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Problem 33

The IUPAC name of the compound given is
(a) $2,2-$ diethyl propane $-1,3-$ dialdehyde
(b) 3,3 - diethyl pentane- 1,5 -dial
(c) $2,2-$ diethyl propane $-1,3-$ dial
(d) 3,3 -dimethyl keto pentane

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Problem 34

The correct bondline structure of 4 -hydroxy $-4$ -methyl pentan-2-one is

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Problem 35

Identify the correct statement among the following
(a) The minimum number of Carbon atoms in a branched alkane is three.
b.is an unsaturated compound.
(c)is known as ethane-1,2-dioic acid.
(d) is known as 2 -ethylbutane.

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Problem 36

IUPAC name of the compound
(a) Trans-3,4-dimethylhex-3-ene
(b) Cis- 3,4 -dimethylhex-3-ene
(c) Cis- 3,4 -dimethylhex-4-ene
(d) Cis-2,3-diethylbut-2-ene

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Problem 37

A compound which exhibits both geometric and optical isomerism among the following is

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Problem 38

The correct statement about $\mathrm{P}, \mathrm{Q}$ and $\mathrm{R}$ is
(a) P and Q are enantiomers.
(b) $\mathrm{P}$ and $\mathrm{Q}$ are diastereomers.
(c) $\mathrm{P}$ and $\mathrm{R}$ are enantiomers
(d) P and Q are identical.

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Problem 39

The number of enantiomeric pairs that are possible on monochlorination of isopentane is
(a) 0
(b) 4
(c) 3
(d) 2

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Problem 40

The wrong statement about resonance is
(a) resonance structures with the greatest number of covalent bonds are most stable.
(b) structures with like formal charges on adjacent atoms have very high energies.
(c) the energy of the resonance hybrid is always higher than the calculated energy of the contributing structure.
(d) resonance with the least number of formal charges are most stable.

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Problem 41

When (-) 3-Methyl pent-1-ene undergoes catalytic hydrogenation,
(a) the product obtained has $(+)$ rotation
(b) the product is obtained with retention of configuration
(c) an optically inactive product is obtained
(d) a racemic mixture is obtained

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Problem 42

A compound which is not a constitutional isomer of

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Problem 43

(a) two representations of the same isomer
(b) enantiomers
(c) constitutional isomers
(d) epimers

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Problem 44

The meso form of 2,3 dichloro butane is

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Problem 45

A compound among the following which shows optical activity is

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Problem 46

A example of a stereo selective reaction is

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Problem 47

The correct increasing order of electron donating effect of $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-,\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-$ and $\mathrm{CH}_{3}-\mathrm{CH}_{2}-$ groups when attached to benzene or unsaturated system is
(a) $\mathrm{CH}_{3}-\mathrm{CH}_{2}-<\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-<\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-$
(b) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-<\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-<\mathrm{CH}_{3}-\mathrm{CH}_{2}-$
(c) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-<\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-<\mathrm{CH}_{3}-\mathrm{CH}_{2}-$
(d) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}<\mathrm{CH}_{3}-\mathrm{CH}_{2}-<\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-$

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Problem 48

(a) Structural isomers
(b) enantiomers
(c) diastereomers
(d) representation of the same isomer

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Problem 49

The correct order of stability of conformations of butane is
(a) anti < gauche $<$ eclipsed
(b) eclipsed < anti < gauche
(c) eclipsed $<$ gauche $<$ anti
(d) gauche $<$ anti $<$ eclipsed

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Problem 50

The specific rotation of a pure optically active compound is $+12^{\circ} .$ The specific rotation of the sample in a reaction with $20 \%$ racemization and $80 \%$ retension of configuration will be
(a) $+12^{\circ}$
(b) $-12^{\circ}$
(c) $+9.6^{\circ}$
(d) $-2.4^{\circ}$

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Problem 51

The above structure cannot be a valid resonance structure for nitro methane because
(a) nitromethane does not show resonance
(b) it is a charged structure
(c) there are ten electrons around nitrogen
(d) Oxygen should have a + charge

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Problem 52

A meso compound
(a) is an achiral molecule, which contain chiral carbons.
(b) contains a plane of symmetry or a centre of symmetry.
(c) is optically inactive due to internal compensation.
(d) is characterized by all the above.

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Problem 53

Geometrical isomerism is exhibited by
(a)
(b)
<smiles>CCC(C)=NO</smiles>
(c) $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}=\mathrm{CH}_{2}$
(d)

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Problem 54

Between $\mathrm{CH}_{3} \mathrm{O} \mathrm{CH}_{2} \mathrm{CH}_{2}(\mathrm{I})$ and $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O} \mathrm{CH}_{2}(\mathrm{II})$
(a) I is more stable because it is $1^{\circ}$ carbocation.
(b) II is more stable because it is $1^{\circ}$ carbocation.
(c) II is more stable because the cation is stabilized by the lone pair on oxygen.
(d) Both are equally stable since both the cations are $1^{\circ}$ and stabilized by oxygen.

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Problem 55

Four pairs of structures are given in (A)- (D)
(a) and
(I)
(II)
(b) $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}-\dot{\mathrm{CH}}_{2}$ and
<smiles>C=CC(C)=CC</smiles>
(I)
(II)
<smiles>[C+]C=CCC</smiles> (c) $\mathrm{H}_{2} \mathrm{C}=\ldots=\mathrm{CH}$, and
(I)
(II)
<smiles>C[C+]CCCC</smiles>
<smiles>C[C+]C=CCCC</smiles> (d) $\mathrm{H}_{3} \mathrm{C}-\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3}$ and
(I)
(II)
The more stable I or II in each pair will be
(a) $\mathrm{A}(\mathrm{I})$
$\begin{array}{llllll}\text { B (I) } & \text { C (II) } & \text { D (II) } & \text { (b) A (II) } & \text { B (II) } & \text { C (I) }\end{array}$
$\mathrm{D}(\mathrm{I})$
(c) $\mathrm{A}(\mathrm{I})$
$\begin{array}{lllll}\mathrm{B} \text { (II) } & \mathrm{C} \text { (I) } & \mathrm{D}(\mathrm{II}) & \text { (d) } \mathrm{A} \text { (II) } & \mathrm{B}\end{array}$
(I)
C (II)
$\mathrm{D}(\mathrm{II})$

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Problem 56

Which among the following is an 'Z' isomer?

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Problem 57

The erythro form of 3 -bromo-2-butanol is

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Problem 58

The incorrect resonance structure of diazomethane is
(a) $\mathrm{H}_{2} \stackrel{\ominus}{\cdots}-\mathrm{N} \equiv \cdots$
(b) $\mathrm{CH}_{3}-\mathrm{N}=\cdots \mathrm{N}$
(c) $\mathrm{H}_{2} \mathrm{C}=\stackrel{\oplus}{\mathrm{N}}=\cdots \mathrm{N}^{\cdot}$
(d) $\mathrm{H}_{2} \mathrm{C} \rightarrow \ddot{\mathrm{N}}=\cdots^{\ominus}$

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Problem 59

A description that does not fit in with the application of resonance among the following is
(a) Resonance is used to explain the stability of phenoxide ion.
(b) Resonance is used to explain the poor reactivity of halogen in chlorobenzene.
(c) Resonance is used to explain the deactivating influence of bromine in bromo benzene.
(d) Resonance is used explain the neutral behaviour of benzamide.

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Problem 60

Identify a statement which is not correct among the following
(a) $\mathrm{C}_{6} \mathrm{H}_{5}$ group in $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{M}_{8} \mathrm{Cl}$ acts as an electrophile.
(b) The two nonbonded electrons of a singlet carbene occupy the same orbital.
(c) The stability of the alkyl carbocation is influenced by resonance.
(d) Free radicals are formed in a homolytic bond fission.

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Problem 61

Assign 'R' and 'S' configuration for the marked I. II and III.
(a) I 'R' II 'S' and III 'R'
(b) I 'S', II 'R', III 'R'
(c) I 'S, II 'S' III 'R'
(d) II 'R', I 'S' III 'S'

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Problem 62

In benzene all the $\mathrm{C}-\mathrm{C}$ bonds are of equal length because of
(a) resonance
(b) aromaticity
(c) hyperconjugation
(d) tautomerism

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Problem 63

Which of the following compounds will have a meso isomer also?
(a) 2 -Bromo $-3$ -chlorobutane
(b) $2,3-$ Dichloropentane
(c) 2 -Hydroxy butanoic acid
(d) 2, 3 -Dibromobutane

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Problem 64

The enol form of acetone after treatment with D.O gives

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Problem 65

The correct decreasing order of nucleophilicity of the following ions for $\mathrm{S}_{\mathrm{N}}{ }^{2}$ reactions in protic solvents is
(a) $\mathrm{PhS}^{-}>\mathrm{PhO}^{-}>\mathrm{OH}^{-}>\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}>\mathrm{CN}^{-}$
(b) $\mathrm{PhS}^{-}>\mathrm{CN}^{-}>\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}>\mathrm{OH}^{-}>\mathrm{PhO}^{-}$
(c) $\mathrm{CN}^{-}>\mathrm{OH}^{-}>\mathrm{C}, \mathrm{H}_{5} \mathrm{O}^{-}>\mathrm{PhS}^{-}>\mathrm{PhO}^{-}$
(d) $\mathrm{C}, \mathrm{H}, \mathrm{O}^{-}>\mathrm{CN}^{-}>\mathrm{OH}^{-}>\mathrm{PhO}^{-}>\mathrm{PhS}^{-}$

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Problem 66

The specific arrangement of atoms that characterize a particular stereoisomer is known as
(a) tautomer
(b) conformation
(c) configuration
(d) geometry

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Problem 67

A bond that undergoes heterolytic cleavage most readily is
(a) $\mathrm{C}-\mathrm{C}$
(b) $\mathrm{O}-\mathrm{H}$
(c) $\mathrm{C}-\mathrm{O}$
(d) $\mathrm{C}-\mathrm{H}$

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Problem 68

The hyperconjugative effect of the group $\mathrm{R}$ in the compound $\mathrm{R}-\mathrm{CH}=\mathrm{CH}_{2}$ follows the order.
(a) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}>\mathrm{CH}_{3}>\mathrm{CH}_{3} \mathrm{CH}_{2}-$
(b) $\mathrm{CH}_{3}->\mathrm{CH}_{3} \mathrm{CH}_{2}->\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-$
(c) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}->\mathrm{CH}_{3}-\mathrm{CH}_{2}->\mathrm{CH}_{3}-$
(d) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}->\mathrm{CH}_{3}-\mathrm{CH}_{2}->\mathrm{CH}_{3}-$

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Problem 69

The isomeric cis $-2$ -butene and trans 2 -butene differ in
(a) the products obtained by addition of $\mathrm{HBr}$
(b) their reduction products on hydrogenation
(c) their products on ozonolysis
(d) the products they give on bromine addition

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Problem 70

Zero inductive effect is shown by
(a) $-\mathrm{CH}_{3}$
(b) $-\mathrm{H}$
(c) $-\mathrm{D}$
(d) $-\mathrm{C}_{6} \mathrm{H}_{5}$

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Problem 71

The least stable cabocation among the following is
(a) $\mathrm{CH}_{3}-\mathrm{CH}_{2}^{+}$
(b) $\mathrm{F}_{3} \mathrm{C}-\mathrm{CH}_{2}$
(c) $\mathrm{F}_{3} \mathrm{C}$
(d) $\mathrm{CH}_{3}-\mathrm{CH}=\stackrel{+}{\mathrm{C}} \mathrm{H}$

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Problem 72

The most stable free radical among the following is
(a)
<smiles>C=CC(C)C</smiles>
(b)
<smiles>c1ccccc1</smiles>
(c) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}$
(d) $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CH}_{2}$.

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Problem 73

The most stable among the isomeric carbocations among $\mathrm{C}_{5} \mathrm{H}_{11}{ }^{+}$ is
(a) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C} \mathrm{CH}_{2} \mathrm{CH}_{3}$
(b)
(c)
<smiles>CCCCCC</smiles>
(d)
<smiles>[C+]CC(C)C</smiles>

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Problem 74

When
<smiles>CCC(C)(C)C</smiles> undergoes rearrangement, the major rearranged ion formed is likely to be

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Problem 75

An example of a molecule which shows optical activity but does not contain chiral carbon atom is
(a) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCHClCH}_{3}$
(b) $2,3-$ Pentadiene
(c) Mesotartaric acid
(d) CH.CH.CHCICH

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Problem 76

The correct decreasing order of acidity is
(a) $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}>\mathrm{HC}=\mathrm{CH}>\mathrm{H}_{2} \mathrm{O}>\mathrm{NH}_{3}$
(b) $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}>\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}>\mathrm{NH}_{3}>\mathrm{HC}=\mathrm{CH}$
(c) $\mathrm{HC}=\mathrm{CH}>\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}>\mathrm{H}_{2} \mathrm{O}>\mathrm{NH}_{3}$
(d) $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}>\mathrm{H}_{2} \mathrm{O}>\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}>\mathrm{HC}=\mathrm{CH}$

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Problem 77

Most stable carbocation among the following is

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Problem 78

Choose the correct compound/species from P-S according to the property indicated in each.
(P) The stronger acid of the two $\left(\mathrm{CH}_{3}\right)_{2} \underset{(\mathrm{I})}{\mathrm{NH}}$ or $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{O} \mathrm{H}$
(Q) The stronger base of the two $\left(\mathrm{CH}_{3}\right)_{3} \ddot{\mathrm{N}}$ or $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{O}$
(III)
(R) The stronger acid of the two $\mathrm{H}_{2} \mathrm{O}$ or $\mathrm{H}_{2} \mathrm{~S}$ "1
(S) The stronger base of the two $\mathrm{OH}$ or $\mathrm{SH}$
(a) $\mathrm{P}-\mathrm{II}, \mathrm{Q}-\mathrm{III}, \mathrm{R}-\mathrm{VI}, \mathrm{S}-\mathrm{VII}$
(b) $\mathrm{P}-\mathrm{I}, \mathrm{Q}-\mathrm{III}, \mathrm{R}-\mathrm{V}, \mathrm{S}-\mathrm{VIII}$
(c) $\mathrm{P}-\mathrm{II}, \mathrm{Q}-\mathrm{IV}, \mathrm{R}-\mathrm{V}, \mathrm{S}-\mathrm{VIII}$
(d) $\mathrm{P}-\mathrm{II}, \mathrm{Q}-\mathrm{III}, \mathrm{R}-\mathrm{V}, \mathrm{S}-\mathrm{VII}$

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Problem 79

4-Nitroaniline is a weaker base compared to 4 -cyanoaniline. This is because
(a) both nitro and cyano are strong electron withdrawing groups.
(b) the lone pair of nitrogen of the $\mathrm{NH}_{2}$ group is delocalised in 4 -nitro aniline and not in 4 -cyanoaniline.
(c) the negative charge resides on the more electronegative oxygen in nitro aniline in the resonance delocalization.
(d) cyano group is aligned planar with the ring.

Supratim Pal

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Problem 80

Identify the isomeric pair among the sets given below (A) - (D)

Supratim Pal

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Problem 81

The correct IUPAC name of $\quad \quad \mid \quad$ is
(a) 2-Chloro-5-Cyanophenol
(b) 3-Cyano-6-Chlorophenol
(c) 4-Chloro-3-hydroxybenzene carbonitrile
(d) 4-Chloro-1-Cyano-3-hydroxybenzene

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Problem 82

Which of the following does not exhibit tautomerism?

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Problem 83

is known as
(a) Bicyclobutyl ketone
(b) 1,4 , trans annular cyclohexanone
(c) Bicyclo [2.2.0] hexan-2-one
(d) Bycyclo [2.2.0] hexan-1-one

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Problem 84

Which of the following is the correct name for the following compound?
<smiles>c1ccc(C2CCCCC2)cc1</smiles>
(a) cyclohexyl benzene
(b) phenyl cyclohexane
(c) hexahydro biphenyl
(d) hexahydrophenyl benzene

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Problem 85

The IUPAC name of
(a) 3 -Methyl pent- 2 -en- 1 -ol
(b) 2 -Ethyl pent- 2 -en-5-ol
(c) 3 -Ethyl-but-2-en-1-ol
(d) 3 , 3 -Methyl ethyl prop-2-en-1-ol

Supratim Pal

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Problem 86

Which is the structural isomer of

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Problem 87

A set which contains an electrophile, a Lewis base and a species containing unpaired electrons among the following is
(a) $\mathrm{Cl}^{-}, \mathrm{AlCl}_{3}$ and $\mathrm{H}_{2}$
(b) $\mathrm{SO}_{3},\left(\mathrm{CH}_{3}\right)_{2} \mathrm{O}$, triplet carbene
(c) $\mathrm{Cl}^{-}, \mathrm{HCl}$ and singlet carbene

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Problem 88

The relationship between
and HO - will be
<smiles>CC(O)C(O)C(C)O</smiles>
(a) two representations of the same molecule
(b) diastereomers
(c) enantiomers
(d) anomers

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Problem 89

Compound in which H- bonding is not possible is

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Problem 90

A compound can exhibit optical activity even if
(a) a rotation axis is present
(b) a mirror plane is present
(c) a centre of symmetry is present
(d) an alternating axis of symmetry is present

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Problem 91

Which of the following is an isomer of 2, 2 -dimethyl propane?
(a) Neopentane
(b) 2-Methyl butane
(c) Cyclopentane
(d) Methyl cyclobutane

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Problem 92

Number of structural isomers possible for $\mathrm{C}_{6} \mathrm{H}_{14}$ and $\mathrm{C}_{7} \mathrm{H}_{16}$ are respectively
(a) 5 and 7
(b) 5 and 9
(c) 6 and 7
(d) 4 and 8

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Problem 93

Inductive effect in organic molecule is observed due to
(a) conjugation
(b) $\pi$ orbitals
(c) electro negativity difference
(d) electron affinity

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Problem 94

The movement of electrons in one of the structures is not shown correctly. Identify the structure.

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Problem 95

Configuration of a chiral molecule can be changed only if
(a) the compound is rotated out of the plane of paper.
(b) the confirmation is changed by rotation.
(c) the Fischer projection is changed to the Newman projection.
(d) the bond to the chiral carbon is broken.

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Problem 96

Which of the following carbanions is most stable?
(a) $\mathrm{CH}_{3} \mathrm{CH}_{2}$
(b) $\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{CH}_{2}^{-}$
(c) $\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{CH}_{2}-\mathrm{CH}_{2}^{-}$
(d) $\mathrm{ClH}_{2} \mathrm{C}-\overline{\mathrm{C}}\left(\mathrm{CH}_{3}\right)_{2}$

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Problem 97

Four sets of carbanions $(a-d)$ with the factors responsible for their stability to a certain extent are given. Identify the carbanion with wrong explanation of stability.
(a) $\mathrm{Cl}_{3} \mathrm{C}^{\Theta}: \mathrm{p} \pi-\mathrm{d} \pi$ bond
<smiles>[C+]1C=CC=CC1</smiles>
(b) $\quad \|:$ aromaticity
(c) hybrid orbitals
(d) $\mathrm{H}_{2} \mathrm{C}-\mathrm{NO}_{2}:$ nucleophilic nature of $\mathrm{NO}_{2}$ group

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Problem 98

Identify the correct resonance pair among the following.

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Problem 99

Four pairs of compounds (A) - (D) are given below. Indicate, in each pair, which compound can be more effectively hydrogen bonded.
(a) $\mathrm{CH}_{3} \underset{(\mathrm{I})}{\mathrm{CH}_{2}} \mathrm{OH}$ and $\mathrm{CH}_{3}-\underset{(\mathrm{IH})}{\mathrm{O}-\mathrm{CH}_{3}}$
(b) $\underset{\text { (I) }}{\left(\mathrm{CH}_{3}\right)}_{3} \mathrm{~N}$ and $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}$
(c) $\mathrm{HOCH}_{2}-\left(\mathrm{CH}_{2}\right)_{4}-\mathrm{CH}_{2} \mathrm{OH}$ and $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}_{\text {(II) }}{\mathrm{C}} \mathrm{HOHCH}_{3}$
(d) $\mathrm{CH}_{3} \underset{\text { (I) }}{\mathrm{CH}_{2}} \mathrm{OH}$ and $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{SH}$
(a) $(\mathrm{A})-(\mathrm{I}),(\mathrm{B})-(\mathrm{I}),(\mathrm{C})-(\mathrm{I}),(\mathrm{D})-(\mathrm{I})$
(b) (A) - (I), (B) - (II), (C) - (I), (D) - (II)
(c) $(\mathrm{A})-(\mathrm{I}),(\mathrm{B})-(\mathrm{I}),(\mathrm{C})-(\mathrm{II}),(\mathrm{D})-(\mathrm{II})$
(d) (A) - (I), (B) - (II), (C) - (I), (D) - (I)

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Problem 100

The number of chiral centres and the stereoisomers possible for the following compound are respectively
(a) 1 and 2
(b) 3 and 8
(c) 2 and 4
(d) 4 and 16

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Problem 101

The number of stereoisomers possible for 2,4 -hexadiene is
(a) 4
(b) 2
(c) 3
(d) 6

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Problem 102

A molecule which is not chiral among those listed below is

Supratim Pal

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Problem 103

Which of the following is not true about a homolytic fission?
(a) The products are free radicals.
(b) The reaction occurs under the influence of heat or light.
(c) It occurs when the bond breakage is between two atoms of the same electronegativity.
(d) Intermediates may undergo rearrangement.

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Problem 104

The weakest acid among those given is
(a) $\mathrm{Cl}_{3} \mathrm{C}-\mathrm{COOH}$
(b) $\mathrm{Br} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH}$
(c) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{COOH}$
(d) $\mathrm{FCH}_{2} \mathrm{COOH}$

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Problem 105

which among the following compounds can exhibit geometrical isomerism?
(a) 2 -phenyl but- 1 -ene
(b) 1 -phenyl but- 2 -ene
(c) 3 -phenyl but-1-ene
(d) 1,1 -dichlorobut- 1 -ene

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Problem 106

Four pairs of compounds are given below. In each pair, one is chiral while the other is achiral. Identify in each pair which is chiral. Choose from the options given
I $\quad \mathrm{ClCH}_{2} \mathrm{CHOHCH}_{2} \mathrm{OH}$ and $\mathrm{HOH}_{2} \mathrm{C.CHClCH}_{2} \mathrm{OH}$
(A)
(B)
II $\quad \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{2} \mathrm{Br}$ and $\mathrm{CH}_{3} \mathrm{CHBrCH}=\mathrm{CH}_{2}$
(A)
(B)
The options are
(b) I A IV B
$\begin{array}{lllll}\text { (c) I A } & \text { II A } & \text { III B } & \text { IV A }\end{array}$
$\begin{array}{lllll}\text { (d) I B II B III B } & \text { IV A }\end{array}$

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Problem 107

Identify the statement which is not correct among the following.
(a) Acetone exists almost $100 \%$ in the keto form.
(b) Acetylacetone exists considerably in the enol form.
(c) Phenol exists almost $100 \%$ in the enol form.
(d) The enol content of $\mathrm{C}_{6} \mathrm{H}_{c}-\mathrm{COCH}_{2} \mathrm{C}_{6} \mathrm{H}_{5}$ is very low.

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Problem 108

The dipolemoment of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl}(2.05 \mathrm{D})$ is considerably larger than that for vinyl chloride $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{Cl}(1.44 \mathrm{D})$ This is because
(a) of hyperconjugation in ethyl chloride.
(b) the unshared electron pair in chlorine is in resonance with the olefinic double bond in vinyl chloride.
(c) Ethane is a saturated molecule.
(d) of the electromeric effect.

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Problem 109

Racemic tartaric acid is optically inactive because
(a) of its meso forms
(b) it has a plane of symmetry
(c) of external compensation
(d) symmetrical nature

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Problem 110

which of the following statements is not correct?
(a) Resonance and tautomerism describe the same phenomenon.
(b) A group with a + I effect, attached to a carbocation, increases the stability of the carbocation.
(c) Weaker the acid, stronger is its conjugate base.
(d) The $-\mathrm{OH}$ and $-\mathrm{NH}_{2}$ group attached to an aromatic ring exert $+\mathrm{M}$ effect.

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Problem 111

Statement 1 All olefinic compounds exhibit geometric isomerism. and
Statement 2
Geometric isomerism in olefins arises due to restricted or hindered rotation between $\mathrm{C}=\mathrm{C}$ bonds.

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Problem 112

Statement 1
Stereoisomers with D-configuration and L-configuration do not refer to compounds with $(+)$ and $(-)$ rotation respectively. and
Statement 2
The letters $\mathrm{D}$ and $\mathrm{L}$ refer to the configuration of atoms or groups at a chiral centre based on $\mathrm{D}$ and $\mathrm{L}$ glyceraldehydes.

Supratim Pal

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Problem 113

Statement 1
Alkyl carbanion such as $\mathrm{CH}_{3}^{-}$ has pyramidal shape. and
Statement 2
The carbon atom carrying the negative charge has an octet of electrons.

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Problem 114

Identify the correct statement among the following
(a) Racemic forms are optically inactive but are resolvable.
(b) can exhibit both geometric and optical isomerism.
<smiles>O=C(O)C(O)C(O)C(O)CO</smiles>
(c) An optically active form of HOOC-CHOH-CHOH-COOH can be represented as
are
(d) and HO $\mathrm{H} \quad$ enantiomers

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Problem 115

The enantiomer of
(a)
(b)
(c)
(d)

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Problem 116

The number of optically active stereoisomers possible for the compound 2,3 -dihydroxy butane are
(a) 4
(b) 2
(c) 6
(d) 8

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Problem 117

The molecules which have dipole moment is/are
(a) $\mathrm{CH}_{2} \mathrm{Cl}_{2}$
(b) 2, 2-dimethylpropane
(c) Cis-3-hexene
(d) p-chloronitrobenzene

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Problem 118

A carbocation can
(a) dimerize
(b) rearrange to give a more stable carbocation
(c) eliminate a proton to give an alkene
(d) add on to a nucleophile to form a stable compound

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Problem 119

Which of the following statements is/are correct about H-bonding?
(a) $\mathrm{n}$ -Butanol has a higher boiling point than diethylether on account of intramolecular H-bonding.
(b) Maleic acid is a stronger acid than fumaric acid due to the stabilization of the resulting anion by intramolecular H-bonding.
(c) $\mathrm{p}$ -nitrophenol is steam volatile due to intramolecular hydrogen bonding.
(d) Hydrogen bond formation intramolecularly involving one molecule only is known as chelation and when formed intermolecularly is known as association.

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Problem 120

Column I Column II
(a) Hydrogen bonding
(p) Conjugate base of phenol
(b) van der Waals forces
(q) azide ion
(c) Nucleophile
(r) non covalent interaction
(d) Resonance stabilization
(s) alcohols

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Problem 121

<smiles>CC(=O)CC(C)=O</smiles> In $\mathrm{H}_{2} \mathrm{C}-\mathrm{C}-\mathrm{CH}_{2}-\mathrm{C}-\mathrm{CH}_{3}($ pentan $-2,4$ -dione $)-$ the hydrogen atoms of the central methylene group $-\mathrm{CH}_{2}$
-are acidic as a phenolic -OH. Account for this.

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Problem 122

Arrange the carbocations $\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{3}^{\oplus}, \stackrel{\oplus}{\mathrm{C}} \mathrm{H}_{3},\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{2}^{\oplus} \mathrm{C} \mathrm{H}$ and $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{C} \mathrm{H}_{2}$ in the increasing order of stability. Justify.

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Problem 123

Two pairs of compounds are given below, which one in each is more acidic and why?
(i) $\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ and $\mathrm{H}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
(ii) $\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ and
<smiles>CCC(C)CCO</smiles>

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Problem 124

Give the enol forms of the following.

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Problem 125

The boiling point of $\mathrm{CH} 3 \mathrm{OH}$ is $65^{\circ} \mathrm{C}$, while the boiling point of $\mathrm{CH} 3 \mathrm{SH}$ is only $6^{\circ} \mathrm{C}$. Explain this difference in boiling point.

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Problem 126

Draw the Fischer and staggered Newmann projection structures of $(+),(-)$ and meso forms of 2,3 -dibromo butane.

Supratim Pal

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Problem 127

When (-) lactic acid is treated with methanol under acidic conditions, (+) methyl lactate, an ester, is obtained as the product. Has the configuration at chiral centre changed?

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Problem 128

Arrange the acids (I-V) listed below in the decreasing order of their acid strength and justify.
(i) Butanoic acid
(ii) Trichloro acetic acid
(iii) Chloroacetic acid
(iv) Trimethyl acetic acid
(v) Bromo acetic acid

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Problem 129

Account for the fact that when 3,3 -dimethyl-2-butanol is treated with HBr, the product formed is 2 -bromo-2,3dimethylbutane and not 3,3 -dimethyl-2-bromobutane as expected.

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Problem 130

Identify the compounds having chiral centres among the following
(i) 1-Bromopentane
(ii) 1-Chloro-2-methylpentane
(iii) 2 -Chloro- 2 -methylpentane
(iv) Citric acid
(v) 1-Chloro-2-bromobutane

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Problem 131

(a) $\alpha$ -methyl-p-bromophenyl acetic acid
(b) 2 - $(4$ -bromophenyl) propanoic acid
(c) 2 -methyl $\mathrm{p}$ -bromophenyl acetic acid
(d) p-bromophenyl propionic acid

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Problem 132

The IUPAC name of $\quad 1$ is
<smiles>CCC(C)CC(CC)CC</smiles>
(a) 5 -heptenylheptane
(b) 3 -heptylhept-3-ene
(c) 3 -(3-heptyl) hept-3-ene
(d) 5,6-Diethyl-3-methyldec-4-ene

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Problem 133

<smiles>ClCCI</smiles>
<smiles>ClC(Cl)(Cl)Cl</smiles> The $\mathrm{Cl}^{\text { }} \mathrm{Cl}$ bond angle in $1,1,2,2$ -tetrachloroethene and tetrachloromethane respectively are about
(a) $90^{\circ}$ and $109.5^{\circ}$
(b) $109.5^{\circ}$ and $120^{\circ}$
(c) $120^{\circ}$ and $109.5^{\circ}$
(d) $120^{\circ}$ and $120^{\circ}$

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Problem 134

The correct structure of DMF is

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Problem 135

A compound with M.F $\mathrm{C}_{8} \mathrm{H}_{14}$ contains 12 secondary and two tertiary $\mathrm{H}$ atoms. The compound is

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Problem 136

The compound which has only one isopropyl group is
(a) $2,2,2,3$ -tetramethyl pentane
(b) 2,4 -dimethyl pentane
(c) $2,2,3$ -tri methyl pentane
(d) 2 -methyl pentane

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Problem 137

The IUPAC name of the following is
(a) Decalin
(c) Bicyclo[4.4.2]decane

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Problem 138

A compound with molecular formula $\mathrm{C}_{7} \mathrm{H}_{16}$ exhibits optical isomerism. The compound is
(a) 2,5 dimethylhexane
(b) $2-2$ -dimethylpentane
(c) 3 -methylpentane
(d) 2,3 -dimethylpentane

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Problem 139

(+) Mandelic acid has an optical rotation of $+158^{\circ}$. What would be the specific rotation of a mixture of $25 \%(-)$ and $75 \%$ (+) mandelic acid?
(a) $+118.5^{\circ}$
(b) $-118.5^{\circ}$
(c) $-79^{\circ}$
(d) $+79^{\circ}$

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Problem 140

Identify the statement which is not correct among the following
(a) $(+)$ and meso tartaric acids are diastereomers.
(b) The enol percentage of acetyl acetone is more than that of acetone.
(c) Meso butane- 2,3 -diol can easily be resolved to give $(+)$ and $(-)$ isomers.
(d) $\mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}$ is known as 3 -methyl-2-butanol.

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Problem 141

A compound which can exist in more than one enolic form is

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Problem 142

An allylic carbocation is less stable than
(a) a vinyl cation
(b) neopentyl cation
(c) benzylic cation
(d) $\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CH}_{2}^{+}$

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Problem 143

A structure which is not permissible for p-nitrophenoxide ion is

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Problem 144

Which of the following carbocations is most stable?
(a) Trityl
(b) benzyl
(c) Diphenyl
(d) $\mathrm{t}$ -butyl

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Problem 145

Which of the following compounds has been incorrectly named?
<smiles>ClC1C=CCCC1</smiles>
(a) $\quad$ 2-chlorocyclohexene
(b) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{Br}$
1-Bromo-3-methylbutane
(c) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CH}-\mathrm{COOH}$
3-methyl but- 2 -enoic acid
(d)
<smiles>CCC(C)C</smiles> 2-cyclopropylbutane

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Problem 146

(a) optical isomers
(b) geometrical isomers
(c) two different representations of the same compound
(d) structural isomers

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Problem 147

An example in which the lone pair of electrons in a heteroatom is used for resonance stabilization among the following is

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Problem 148

A free radical is
(a) generated by a heterolytic cleavage
(b) paramagnetic
(c) generally more stable than a carbanion
(d) produced in an ionic reaction

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Problem 149

(a) geometrical isomers
(b) enantiomers
(c) diastereomers
(d) same compound

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Problem 150

Four carbocations (I) - (IV) are given below
(I) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{Cl}$
(II) $\mathrm{CH}_{3} \mathrm{CH} \mathrm{CH}_{3}$
(III) $\mathrm{CH}_{3} \mathrm{CH} \mathrm{COCH}_{3}$
(IV) $\mathrm{CH}_{3} \mathrm{OCH} \mathrm{C}_{2} \mathrm{H}_{5}$
The increasing order of stability of the cations will be
(a) $(\mathrm{IV})<(\mathrm{I})<(\mathrm{II})<(\mathrm{III})$
(b) $(\mathrm{III})<(\mathrm{I})<(\mathrm{II})<(\mathrm{IV})$
(c) $(\mathrm{IV})<(\mathrm{III})<(\mathrm{I})<(\mathrm{II})$
(d) (IV) $<(\mathrm{III})<(\mathrm{II})<(\mathrm{I})$

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Problem 151

The most stable carbocation among the following is

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Problem 152

Identify the correct statements among the following
(I) Removal of a proton from $\left(\mathrm{H}_{3} \mathrm{C}\right)_{2} \mathrm{CH}-\mathrm{CH}-\mathrm{CH}_{3}$ leads to a more stable carbocation.
(II) The hydrogen bonding is strong in $\mathrm{S}-\mathrm{H}-\mathrm{-} \mathrm{S}$.
(III) The central carbon atom in a $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}^{\bullet}$ free radical possesses 5 electrons.
(IV) The number of $\sigma$ bonds in but-1-en-3-yne is 7 .
(a) all are correct
(b) (IV) only'
(c) (I) and (IV) only
(d) (I), (III) and (IV)

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Problem 153

$\mathrm{pK}_{\mathrm{a}}$ value is least for
(a) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{COOH}$
(b) $\mathrm{BrCH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{COOH}$
(c) $\mathrm{CH}_{3}-\mathrm{CCl}_{2}-\mathrm{COOH}$
(d) $\mathrm{CH}_{3}-\mathrm{CHCl}-\mathrm{COOH}$

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Problem 154

Least stable among the carbanions given is

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Problem 155

The enol form of is;

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Problem 156

In which of the following compounds nitrogen is most basic?

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Problem 157

Homolytic bond fission is observed in
(a) Syn addition of bromine to ethylene
(b) trans addition of bromine to butene
(c) halogenation of alkanes
(d) nitration of benzene

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Problem 158

The correct IUPAC name of $\mathrm{CH}_{3}-\mathrm{O}-\mathrm{CH}_{2}-\mathrm{O}-\mathrm{CH}_{2}-\mathrm{O}-\mathrm{CH}_{3}$ is
(a) $1,3,5$ -Trioxabutane
(b) $2,4,6$ -Trioxabutane
(c) $2,4,6$ -Trioxaheptane
(d) Dimethoxydimethyl ether

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Problem 159

The configuration of chiral carbon atoms in the following compound is
(a) $2(\mathrm{R}), 3(\mathrm{~S})$
(b) $2(\mathrm{~S}), 3(\mathrm{R})$
(c) $2(\mathrm{~S}), 3(\mathrm{~S})$
(d) $2(\mathrm{R}), 3(\mathrm{R})$

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Problem 160

Strength of a $\mathrm{H}$ -bond is
(a) as good as a covalent bond
(b) between van der Waals forces and covalent bond
(c) equivalent to a dipole-dipole interaction
(d) between an ionic and covalent bond

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Problem 161

The strongest H-bonding is observed in
(a) $\mathrm{O}-\mathrm{H}-\mathrm{-} \mathrm{O}$
(b) $\mathrm{N}-\mathrm{H}-\mathrm{N}$
(c) $\mathrm{F}-\mathrm{H}-\mathrm{O}$
(d) $\mathrm{F}-\mathrm{H}-\mathrm{F}$

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Problem 162

In which of the following the lone pair of electrons on the hetero atom do not take part in delocalization?

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Problem 163

The most reactive among the nucleophiles given is
(a) $-\mathrm{OCH}_{3}$
(b) $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}^{-}$
(c) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}$
(d) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CO}^{-}$

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Problem 164

Significant dipole moment is shown by
(a) p-dichlorobenzene
(b) $\mathrm{CO}_{2}$
(c) cis 1,2-dichloroethene
(d) trans 1,2 dichloro 1 -pentene

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Problem 165

The maximum number of isomers for the compound with molecular formula C IBrClF is
(a) 4
(b) 5
(c) 6
(d) 7

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Problem 166

Identify the statement which is not correct.
(a) Diastereomers are always optically active.
(b) $\mathrm{HC} \equiv \mathrm{C}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CHOHCH}_{3}$ is known by the IUPAC name as hex-5-yn-2-ol.
(c) An achiral molecule is one which has a super imposable mirror image.
(d) Only one monochloro derivative is possible for neopentane.

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Problem 167

The specific rotation of an isomer of an alkyl halide X containing one chiral arbon atom is $+40^{\circ} .$ During a reaction in solution, it undergoes partial racemization. If the specific rotation of the equilibrium mixture is $+10^{\circ}$, the ratio of moles of $(+) X$ and $(-) X$ at equilibrium is
(a) $2: 3$
(b) $5: 3$
(c) $3: 2$
(d) $4: 3$

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Problem 168

The heat of hydrogenation of cyclohexene is $127 \mathrm{~kJ} \mathrm{~mol}^{-1} .$ When a second double bond is introduced in the molecule, the heat of hydrogenation of the diene is found to be $231 \mathrm{~kJ} \mathrm{~mol}^{-1} .$ The diene is most likely
(a) Hexa- 1,4 -diene
(b) Hexa- 1,3 -diene
(c) Hexa- 1,5 -diene
(d) Hexa-1, 2-diene

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Problem 169

Most stable among the free radicals given is:

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Problem 170

The dipole moment of vinyl chloride is lower than that of ethyl chloride. This is because of
(a) resonance
(b) inductive effect
(c) Hyperconjugation
(d) unstable nature of vinyl chloride

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Problem 171

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1
n-propyl free radical is more stable than allyl free radical though both of them contain unpaired electron on a primary carbon.
and
Statement 2
Allyl radical is stabilized by resonance.

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Problem 172

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 Stereoisomers which do not have an object and mirror image relationship can be termed as diastereomers. and
Statement 2
An organic compound having only one chiral centre cannot have diastereoisomers.

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Problem 173

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1
Two enantiomeric pairs are found among the monobromination products of 2 -methylbutane. and
Statement 2
There is only one chiral centre in the starting material.

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Problem 174

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 Heterolytic fission of $\mathrm{C}-\mathrm{C}$ bond in propane will give mainly ethyl carbocation and methyl carbanion. and
Statement 2
Ethyl carbocation is stabilized by inductive effect and among unsubstituted carbanions $\mathrm{CH}_{3}^{-}$ is the most stable one.

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Problem 175

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 2,3 -pentadiene $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{C}=\mathrm{CH}-\mathrm{CH}_{3}$ has no chiral carbons, but it is optically active. and
Statement 2
The planes of the two double bonds in 2,3 -pentadiene are different.

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Problem 176

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1
All carbon atoms in but-2-ene lie in one plane. and
Statement 2
All the carbon atoms in but-2-ene are sp $^{2}$ hybridized.

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Problem 177

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1
Tropylium cation is more stable than benzyl cation. and
Statement 2
The tropylium cation is a rearranged and ring expanded form of a benzyl cation.

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Problem 178

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 o-Nitrophenol is steam volatile whereas p-nitrophenol is not steam volatile.
and
Statement 2
There is intra molecular hydrogen bonding in o-nitrophenol, whereas there is intermolecular hydrogen bonding in p-nitrophenol.

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Problem 179

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1
p-Nitrobenzoic acid is more acidic than $\mathrm{p}$ -methyl benzoic acid. and
Statement 2
Substituted benzoic acids are always stronger than benzoic acid.

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Problem 180

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
(a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1
(b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement-1
(c) Statement- 1 is True, Statement- 2 is False
(d) Statement- 1 is False, Statement- 2 is True
Statement 1 Generally geminal diols (two-OH groups attached to the same carbon) are not stable. However chloral hydrate $\mathrm{Cl}_{3} \mathrm{C}-\mathrm{CH}(\mathrm{OH})_{2}$ is stable.
and
Statement 2
Chloral is used in the preparation of DDT.

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Problem 181

A chemical reaction is one in which old bonds are broken and new bonds are made. During the course of these changes a variety of intermediates are formed before a starting material is converted to final products. Formation of these intermediates depend on several factors like bond energies, kinetics of the reactions etc.
When a carbene $: \mathrm{CH}_{2}$ is formed as an intermediate, the final product formed when one of the substrates is ;

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Problem 182

A chemical reaction is one in which old bonds are broken and new bonds are made. During the course of these changes a variety of intermediates are formed before a starting material is converted to final products. Formation of these intermediates depend on several factors like bond energies, kinetics of the reactions etc.
Identify the correct statement among the following.
(a) An electrophile has always a positive charge.
(b) $\mathrm{CN}^{-}$ can act as an ambident nucleophile.
(c)
The carbon species A formed is a methyl carbanion.
(d) In $\mathrm{CH}_{3} \mathrm{MgBr}$, the methyl group carries slight positive charge.

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Problem 183

A chemical reaction is one in which old bonds are broken and new bonds are made. During the course of these changes a variety of intermediates are formed before a starting material is converted to final products. Formation of these intermediates depend on several factors like bond energies, kinetics of the reactions etc.
In which of the following choices, the correct order is not indicated.
(a) $\mathrm{F}^{-}<\mathrm{Cl}^{-}<\mathrm{Br}^{-}<\mathrm{I}^{-}($ the order of base strength $)$
(b) $\mathrm{ClCH}_{2} \underset{\oplus}{\mathrm{C}}\left(\mathrm{CH}_{3}\right)_{2}<\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}<\left(\mathrm{CH}_{3}\right)_{2} \mathrm{COCH}_{3}$ (stability of carbocation)
(c) $\mathrm{O}_{2} \mathrm{~N}-\mathrm{CH}_{2}>\mathrm{CH}_{3}>\mathrm{CH}_{3} \mathrm{CH}_{2}$ (stability of carbanion)
(d) $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}<\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{3}<\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2}$ (stability of alkenes)

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Problem 184

Stereoisomers are different from constitutional isomers in that the former differ from each other in the spatial arrangements while the latter differ on the basis of connectivity of atoms.
The two compounds are related as
(a) diastereomers
(b) enantiomers
(c) configurational isomers
(d) two different compounds

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Problem 185

Stereoisomers are different from constitutional isomers in that the former differ from each other in the spatial arrangements while the latter differ on the basis of connectivity of atoms.
The threo isomer among the following is:

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Problem 186

Stereoisomers are different from constitutional isomers in that the former differ from each other in the spatial arrangements while the latter differ on the basis of connectivity of atoms.
Four structures (I) - (IV) are given below
Two diastereomeric structures among those given are
(a) (I) and (IV)
(b) (I) and (II)
(c) (I) and (III)
(d) (III) and (IV)

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Problem 187

Keto-enol tautomerism is a special type of isomerism involving the 1,3 shift of a proton. There exists an equilibrium between keto and enol forms. In most cases keto form is more stable while in certain cases enol form is favoured.
In which of the following, enol form dominate over the keto form?

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Problem 188

Keto-enol tautomerism is a special type of isomerism involving the 1,3 shift of a proton. There exists an equilibrium between keto and enol forms. In most cases keto form is more stable while in certain cases enol form is favoured.
The identification of the two enol forms of $\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{COCH}_{2} \mathrm{CH}_{3}$ (Hexane-2,4-dione) can be established by the study of
(a) intra molecular H-bonding
(b) colour reaction of the enol with neutral $\mathrm{FeCl}_{3}$
(c) kinetics of the formation of the enol
(d) ozonolysis

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Problem 189

Keto-enol tautomerism is a special type of isomerism involving the 1,3 shift of a proton. There exists an equilibrium between keto and enol forms. In most cases keto form is more stable while in certain cases enol form is favoured.
One which is not a tautomeric pair among the following is :

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Problem 190

Identify the correct statements among the following.
(a) Acetate ion ( $\left.\mathrm{CH}_{3}-\mathrm{COO}^{-}\right)$ is a weaker base than ethoxide ion $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}\right)$.
(b) HF has higher boiling point than HCl.
(c) Tartaric acid (HOOC - CHOH - CHOH - COOH) has three optically active isomers.
(d) $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{CN}$ is known as propyl cyanide as well as butane nitrile.

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Problem 191

Which of the following molecules have only one type of hybridized carbon?

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Problem 192

Which of the following compounds are named correctly according to the IUPAC rules?

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Problem 193

Which of the following show the correct order of nucleophilicity?
(a) $\mathrm{CH}_{3} \mathrm{~S}^{-}>\mathrm{CH}_{3} \mathrm{O}^{-}$
(b) $\left(\mathrm{CH}_{3}\right)_{3} \ddot{\mathrm{N}}>\left(\mathrm{CH}_{3}\right)_{3} \ddot{\mathrm{P}}$
(c) $\mathrm{CN}^{-}>\mathrm{Cl}^{-}$
(d) $\mathrm{OCH}_{3}^{-}>\mathrm{OH}^{-}$

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Problem 194

In which of the following reactions, new chiral centre(s) is/are generated.
(a) $\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{3} \stackrel{\text { Baeyer'sreagent }}{\longrightarrow}$
(b) $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{3}+\mathrm{HBr} \rightarrow$
(c)
(d) $\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HCl} \rightarrow$

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Problem 195

Which of the following statements are correct?
(a) Singlet carbene is paramagnetic.
(b) In the two species $\mathrm{CN}^{-}$ and $\mathrm{CO}$, the common feature is that bond order is three and they are isoelectronic.
(c) Between $\mathrm{CH}_{3} \mathrm{Cl}$ and $\mathrm{CH}_{2} \mathrm{Cl}_{2}$, the former has a higher dipole moment.
(d) In the species $\mathrm{CH}_{3}-\mathrm{C}^{2} \mathrm{H}+\mathrm{HCN} \stackrel{\mathrm{H}_{3}}{\longrightarrow}$ the order of acidity with respect to the positions indicated is $(2)>(1)>(3)$

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Problem 196

Which of the following species is/are stabilized by isovalent hyperconjugation?
(a) Free radicals
(b) Carbanion
(c) Alkenes
(d) Carbocations

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Problem 197

Which of the following pairs are isostructural?
(a) ${\mathrm{C}} \mathrm{C}_{3}$ and $\mathrm{CH}_{3}^{-}$
(b) $\ddot{\mathrm{N} H}_{3}$ and $\mathrm{CH}_{3}^{-}$
(c) $\ddot{\mathrm{N} H}_{3}$ and $\mathrm{CH}_{3}^{-}$
(d) $\mathrm{BCl}_{3}$ and $\mathrm{CH}_{3}{ }^{+}$

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Problem 198

Match the elements of Column I to elements of Column II. There can be single or multiple matches.
Column I
(a) Carbocation
(b) Free radicals
(c) Singlet carbene
(d) Triplet carbene
Column II
(p) $\mathrm{sp}^{2}$ hybridization
(q) paramagnetic
(r) diamagnetic
(s) linear

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Problem 199

Match the elements of Column I to elements of Column II. There can be single or multiple matches.
Column I
(a) Diastereomers
(b) Chiral centres
(c) Tautomers
(d) pent-2-ene
Column
(p) spontaneously interconvertible
(q) cis-trans isomerism
(r) restricted rotation
(s) stereoisomerism

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Problem 200

Match the elements of Column I to elements of Column II. There can be single or multiple matches.
Column I
(a) Free radicals
(b) Photochemical reaction
(c) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CHCH}_{3}$
(d) No bond resonanceColumn II
(p) halogenation of alkanes
(q) homolytic cleavage
(r) hyperconjugation
(s) chain reaction

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