atoz chemistry general organic chemistry - part 1 general

AtoZ CHEMISTRY General Organic Chemistry - Part 1

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General Organic Chemistry - Part 1

1. Hybridisation in Organic Chemistry Q 1. The concept of hybridization is given

(A) to know the structure of a chemical species

(B) to explain the structure of a chemical species

given by VSEPR model

(C) to know the more stable structure

(D) to do energy conservation

Q 2. The process of hybridization is

(A) Exothermic (B) Endothermic

(C) Neither Exothermic nor Endothermic

(D) can be Exothermic or Endothermic

Q 3. Direct participation of atomic orbital of carbon in

CH4 molecule formation leads to

(A) Bond angle equal to 90o

(B) Bond angle equal to 109o28’

(C) Three C – H bonds are equivalent

(D) both A & C

Q 4. Which of the following is NOT characteristics of

hybridization?

(A) it is intra-atomic porcess

(B) No of orbitals remained conserved in

hybrisiation.

(C) Hybridisation can happen between any set of

atomic orbitals.

(D) In any molecule, hybridistion may or may not

occur

Q 5. When ground state C-atoms are subjected to

react, they normally undergo three process –

excitation, hybridization and bonding

simultaneously . Now which of the following

statements is (are) true

(A) Excitation is endothermic , hybridization is

exothermic and bonding is endothermic

(B) All are exothermic

(C) All are endothermic

(D) Excitation is endothermic hybridization is

neither exothermic nor endothermic and bonding

is exothermic.

Q 6. Which of the energy relations is(are) correct?

(A) E2p > E2sp3 > E2sp2 > E2sp > E2s

(B) E2s > E2sp > E2sp2 > E2sp3 > E2p

(C) E2sp2 = E2s > E2p +E2p+E2p

(D) E2sp3 = E2s + E2p + E2p + E2p

Q 7. Which of the following is the correct order of size

(A) 2s > 2sp > 2sp2 > 2sp3 > 2p

(B) 2p > 2sp3 >2sp2> 2sp > 2s

(C) 2sp3 > 3p > 2p

(D) 2sp3 > 3s > 2s

Q Q 8. In 2sp hybridization, 2s orbital can be mixed with

(A) Only 2px (B) Only 2py

(C) Only 2pz

(D) any one of 2px- 2py and 2pz

Q 9. In sp2 orbital, character of pz will be

(A) always 33.33% (B) always 0%

(C) always 66.66% (D) either 33.33% or 0%

Q 10. In sp3orbital

(A) Characters of px, py and pz are equal

(B) Character of s, px,py and pz are equal

(C) s-character is more than pz character

(D) Character of px,py and pz are not equal

Q 11. Which is the correct order of electronegativity?

[CBSE PMT 2006]

(A) sp3C > sp2C > sp3C

(B) spC > sp2C > sp3C

(C) sp2C > sp C > sp3C

(D) sp3C > sp C > sp2C

Q 12. The relative strength of the σ-bond formed

between SP3 – SP3, SP2 – SP2, and SP – SP

(A) 2: 1.99 : 1.93 (B) 2: 1.93 : 1.73

(C) 1.99 : 1.93: 1.73 (D) None of these

Q 13. Overlapping powers (overlap integrals) of 2s, 2p,

2sp3, 2sp2 and 2sp orbitals are in the order

(A) 2s>2p>2sp3>2sp2>2sp

(B) 2p>2s>2sp3>2sp2>2sp

(C) 2sp3>2sp2>2sp>2p>2s

(D) 2sp3>2sp2>2sp>2s>2p Q 14. Which of the following statements is/are true

about for C – O bonds of

(A) Two C-O bonds are formed by sp2 –sp3

overlaps and two C-O bond are formed by sp-sp

overlaps.

(B) Two are formed by sp –p overlaps and two

are formed by sp –p overlaps.

(C) All four C-O bonds are formed by sp-sp

overlaps.

(D) All four C-O bonds are formed by sp-p

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overlaps. Both C-N bonds are formed by sp2 –sp3

overlaps.

Q 15. In this molecule.

NHC

H

(A) both C-N bonds are formed by sp2- sp2

overlaps.

(B) one C-N bond is formed by sp2-sp2 overlaps

while the other by sp2 –sp3

(C) both C-N bonds are formed by sp2-sp3

overlaps.

(D) one C-N bond is formed by sp2-sp3 overlaps

while the other by sp3-sp3 overlap.

Q 16. Assertion (A): All the carbon atom in

CH2=C=CH2 are SP2 hybridised.

Reason (R): In this molecule, all carbon atoms

are attached together by double bonds.

. [NCERT Examaplar]

(A) Both A & R are correct and R is the correct

explanation of A

(B) Both A & R is correct but R is not correct

explanation of A

(C) Both A & R are not correct

(D) A is not correct but R is correct

Q 17. CH2=C=CH2, In this molecule

(A) All C-atoms are sp2-hybridized.

(B) Two C-atoms are sp2- hybridized and one C-

atom is sp-hybridized.

(C) All carbons are sp hybridized

(D) None of the C-atoms is hybridized.

Q 18. Which of the following compounds has

maximum number of sp-hybridized C-atoms?

(A) (CN)2

(B) H2C=CH-CN

(C) HC C–CH2 –CH= C=C=CH2

(D) CH2= C=CH–CN

Q 19. The compound 1,2-butadiene has [IIT JEE 1983]

(A) only sp hybridised carbon atoms

(B) only sp2 hybridised carbon atoms

(C) both sp and sp2 hybridised carbon atoms

(D) sp, sp2 and sp3hybridised carbon atoms

Q 20. Which of the following possess a SP carbon in its

structure? [CBSE PMT 1989]

(A) 3CH CHCl COOH− −

(B) H C C Cl− −

(C) Cl CH CH Cl− = −

(D) 2 2ClCH CH Cl−

2. Characteristics of Hybridisation

Q 1. Molecule in which the distance between the two

adjacent carbon atoms is largest is

(A) ethane (B) ethane

(C) ethyne (D) benzene

Q 2. The bond between carbon atom (1) and carbon

Atom (2) in compound 2N C CH CH − =

Involves the hybrids as [1987-IIT]

(A) sp2 and sp2 (B) sp3 and sp

(C) sp and sp2 (D) sp and sp

Q 3. The hybridisation of carbon atoms in C-C single

bond HC C-CH=CH2 is [1991-IIT]

(A) sp3-sp3 (B) sp2-sp3

(C) sp-sp2 (D) sp3-sp

Q 4. In the compound CH2=CH-CH2-CH2-C CH the

C2-C3 bond is of the type [1999 IIT]

(A) sp-sp2 (B) sp3-sp3

(C) sp-sp3 (D) sp2-sp3

Q 5. The number of sigma and pi-bonds 1-butene-3-

yne are [1989-IIT]

(A) 5 sigma and 5 pi (B) 7 sigma and 3 pi

(C) 8 sigma and 2 pi (D) 5 sigma and 4 pi

Q 6. How many σ and bonds are there in the

molecules of tetracyanoethylene ?

(A) Four σ and fourteen bonds

(B) Five σ and thirteen bonds

(C) Eight σ and ten bonds

(D) Nine σ and nine bonds

Q 7. Allyl Isocynide has [IIT 1995S]

(A) Nine σ and four bonds

(B) Eight σ and Five bonds

(C) Nine σ, Three bonds & 2 non bonded e–

(D) Eight σ, three bonds & 4 non bonded e–

Q 8. The C-H bond distance is the longest in

[1989-IIT]

(A) C2H2 (B) C2H4

(C) C2H6 (D) C2H2Br2

Q Q 9. The carbon-chlorine bond is the shortest in

(A) CH3-Cl (B) C6H5-CH2-Cl

(C) CH2 = CH-Cl (D) CH2=CH-CH2-Cl

Q 10. The x yC C− bond length order in

CH – CH – CH = CH3 2 2

X Y

(i)

CH – CH = C = CH3 2

X Y

(ii)




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(A) i ii iii (B) iii ii i

(C) ii iii i (D) iii i ii

Q 11. The bond length order of indicated bonds in

following molecules are

(1) (2)

(3) (4)

(A) 4 1 2 3 (B) 4 1 3 2

(C) 4 3 1 2 (D) None of these

Q 12. The total number of bond angles in

3 2CH CH CH− = is

(A) 10 (B) 12

(C) 8 (D) 16

Q 13. The Cl – C – Cl angle in 1,1,2,2 –

tetracholoroethene and tetrachloromethane

respectively will be about [IIT – 1988]

(A) 120o & 109.5o (B) 90o& 109.5o

(C) 109.5o & 90o (D) 109.5o & 120o

Q 14. The total number of bond angles in

is

(A) 8 (B) 7

(C) 12 (D) None of these

Q 15. Which of the following is a planar molecule?

(A) 3 2CH CH CH− = (B) 2CH C OH= −

(C) 2H C NH= (D) None

Q 16. Which of the following is a planar molecule?

(A) 2 2CH C CH= =

(B) 2 2CH C C CH= = =

(C) (D)

Q 17. In which of the following molecules, all atoms are

coplanar? [NEET 2016 - II]

(A) (B)

(C) 3 2 2( ) ( )CH C C CN= (D)

Q 18. Indicate the hybridization of all atoms (except H

atoms) in following molecules.

(A) (B)

(C) (D)

(E) (F)

(G)

(H)

(I) (J)

(K) (L)

(M) (N)

(O) (P)

Q 19. In which of the following molecules all atoms are

In one plane (Molecule is Co-planar)?

CH – CH – CH – CH3 2 2 3

X Y

(iii)

H – C C – H H – C N

H C = O2 H C = CH2 2

CH – C – NH3 2

O

ICl

F Br

CH3

CH – C – CH = CH3 2

O

CH CONH3 2

CH CH COOCH3 2 3

CH = C = O2

CHO

CHOCOOH

COOH

CH = C = CH – C C – CH2

CN

CHOCH NO3 CH – O – N = O3

O

CH – C – CH3 3

O

CH CN3 CH – OH3

CH – OH3 2

3




28

(A) (B)

(C) ( )4

C CN (D)

(E) (F)

(G) (H)

(I) (J)

(K) (L)

Q 20. In which of the following molecule all bonds

angles are similar?

(A) (B)

(C) (D)

(E) (F)

(G)

(H)

(I)

(J) (K)

Q 21. How many bond angles are present in following

Molecules?

(A) (B)

(C)

(D) CH2O (E) CH3COCH3

(F) CH2=CH-CH=CH2

3. Resonance

Q 1. In 23CO −

, which statement is true ?

(A) one C-O bond has double bond character &

two C-O bond has single bond character

(B) one C-O bond length is smaller than other

two C-O bond length

(C) All three C-O bonds are identical

(D) 3 C-O bonds are different from each other

Q 2. Delocalization of electrons increases molecular

stability because

(A) electrons-nuclei attraction increases

(B) electron- electron repulsion decreases

(C) Potential energy of the molecule increases

(D) Potential energy of the molecule decreases

Q 3. Which of the following statements is Not true

about resonance?

(A) Resonance is an intramolecular process.

(B) Resonance involves delocalization of both

Electrons & Atoms.

(C) Resonance involves delocalization of

electrons only.

(D) Resonance decreases potential energy of a

molecule.

CH2

C

CH2

C = C

CN

CN

NC

NC

Br

OO

O

O

O

COOCH3

COOCH3

CHO

CH3

CH = CH – CH = CH – OCH2 3

CH = C = CH2 2

CH = CH – CHO2

CH2

O

CHO

CHO

– CH – CH2 3

O

O

H2C = CH – CN




29

Q 4. Which of the following statements is (are) true

about resonance?

(A) Resonance has no effect on the potential

energy of a molecule.

(B) Any resonating molecule is always more

stable than any non-resonating molecule.

(C) The canonical structure explains all features

of a molecule.

(D) The resonance hybrid explains all features of

a molecule.

Q 5. All canonical structures of molecule

(A) must have different numbers of paired

electrons.

(B) need not be always equivalent but they should

not differ much in stability.

(C) should be always equivalent

(D) must have electrons in different orbitals.

Q 6. Resonance energy is

(A) equal to the energy of resonance hybrid.

(B) equal to the energy of most stable canonical

structure.

(C) equal to the difference in energy of the least

stable canonical stable to romance hybrid.

(D) equal to the difference in energies of the most

stable canonical structure & resonance hybrid.

Q 7. In which of the given lone pair of electrons are

not in same plane with the P P− bonds

(A) (B)

(C) 2 2CH CH N CH• •

= − = (D)

Q 8. In which of the following, resonance is not

possible

(A) (B)

(C) (D)

Q 9. Which of the following groups can not participate

in resonance with other suitable group?

(A) (B)

(C) (D)

(E) (F)

(G) (H)

(I) (J)

(K)

Q 10. Which of the following groups can either donate

or withdraw a pair of electrons in resonance

depending upon situation?

(A) 2NO− (B) NO−

(C) 2CH CH− = (D) CHO−

(E) 2NH− (F) N NH− =

(G) Ph−

(H) (I)

(J) Q 11. Write the canonical structures and resonance

hybrid of each of the following?

(A) 3 2CH NO (B) 3CH COOH

(C) 3CH COONa (D)

(E) 2H N CHO−

(F) 2 2CH CH CH

= −

(G) (H)

(I) 2 2CH CH CH

= − (J) 2 2CH CH CH•

= −

(K) 2R CO CH CH− − =

– COOH – COO

– COCl – NH3

– CH2

– CH2

CH = N –2

CH3

O N2 MeO

CH3

CH = CH – N2

CH 3

CH 3

N

H

O O

(L) BH

2 (M) PPh3

CH = CH-

CH- 2

-CH – CH 2 2

CH = O - 2




30

(L) 2 3CH O CH CH NMe

− = −

(M) RCOCl (N) 2HCONH

(O) (P)

(Q) 2CH CH CH O= − = (R)

2CH C CH

= =

(S) 2CH CH C CH− − =

(T) 2 2CH CH CH CH= − =

(U) (V)

(W) 2CH N N

= = (X) 2CH C O= =

(Y) (Z)

Q 12. In which of the following charges is not

resonance stabilized, show by writing canonical

structures?

(A) (B)

(C) 2CH CH

= (D) 2CH CH CH O

− = −

(E) 3 2CH O CH

= − (F) 2 2CH O CH CH

= − =

(G)

(H)

(I) 2 3CH CH N Me

= −

(J) 2 2 2CH CH CH CH

= − −

(K) 2 3CH CH P Me

= −

(L) (M)

(N) (O) 2CH C CH

= =

(P) 2CH C CH

= =

Q 13. The bond order of Carbon Carbon bonds in

benzene is [IIT – 1981]

(A) one (B) Two

(C) between one & two

(D) one & two, alternatively

4. Drawing Resonating Structure

Q 1. Which of the following is correct order of +R

effect of groups

I. II.

III. IV.

(A) II I III IV (B) I II III IV

(C) II III I IV (D) IV III II I

Q 2. Which of the following is correct order of –R

effect of groups

I. 2NO− II. CN−

III. IV.

(A) I II III IV (B) I III II IV

(C) IV III II I (D) I IV III II

Q 3. In which of the given example 2CH CH= −

does not act as +R group?

OH

O

O

O

N

CH2

N|

H

N|

H

CH2 = C – CH = CH3

CH2 = O – CH = CH2




31

(A) (B)

(C) (D)

Q 4. In which of the given example, 2CH CH= −

does not act as R− group

(A) (B)

(C) (D)

Q 5. How many lone pair of electrons participated in

resonance in the given compound

(A) 5 (B) 1

(C) 4 (D) 2

Q 6. In which of the given lone pair of nitrogen is not

participated in resonance

(A) (B)

(C) (D) None of these

Q 7. In which of the given resonance between two

benzenoid ring is not possible

(A)

(B)

(C)

(D) None of these

Q 8. The incorrectly matched total number of

resonance structure (RS) is

(A)

(B)

(C)

(D)

Q 9. In which of the given compound resonance is

possible ?

(A) 2 3CH CH SiH= − (B) 2 2CH CH BH= −

(C) 2 2CH CH NH= − (D) All of these

Q 10. In the given compound ?

(A) 2NO− acts as R− group

(B) 2NH− act as R+ group

(C) OH− does not act as +R group

(D) All of these

Q 11. Which of the following is not a permissible

resonating form

(A) (B)

(C) (D)

Q 12. Which of the following pairs is not a resonating

structures?

(A)

N

N

H

N

:

:

: :

N

:

= CH2

N

NH2:

CH3 CH3

N

:

CH3CH3

CH3CH3

N

:

CH3CH3

CH3CH3

O N2

CH3

CH3

CH3

NO2

Br

BrCH3

CH3 NO2

:

R.S = 5

SO R.S. = 64

2–

CH = CH – CH = CH – CH R.S. = 32 2

:

PO R.S. = 34

3–




32

(B)

(C)

(D)

Q 13. Which of the following is not resonating structure

of diazomethane?

(A) (B)

(C) (D) All of these

Q 14. Which of the following pairs of structure do not

represent resonating structures?

(A)

(B)

(C)

(D)

5. Stability of Resonating Structures

Q 1. A canonical structure will be more stable if

(A) it has more number of bonds than if it has less

number of bonds.

(B) the octets of all atoms are complete than if

octets of all atoms are not complete.

(C) it has charge separation than if it has no

charge separation.

(D) it involves cyclic delocalization of (4n+2)π

electrons than if it involves acyclic

delocalization of (4n+2)π - electrons.

(E) it involves cyclic delocalization (4n)π –

electrons than if it involves acyclic

delocalization of (4n)π – electrons.

(F) +ve charge is on more electronegative atom if

+ve charge is on less electronegative atom.

Q 2. Select the compounds/ions in which resonance is

not possible.

(A) 4 (B) 2

(C) 6 (D) 8

Q 3. HNCO is isocyanic acid exists as following

resonating structures

The correct stability order

(A) I III II (B) I II III

(C) II III I (D) II I III

Q 4. Which of the given is least stable resonating

structure ?

(A)

(B)

(C)

(D)

Q 5. The correct stability order of the following

compounds is

(I) (II)

(III) (IV)

(A) I II III IV (B) IV I II III

(C) IV I III II (D) IV II I III

Q 6. Identify more stable canonical structure in each of

the following pairs?

(A)

C

O

H OH

C

O

H OH




33

(B)

(C)

(D)

(E)

(F)

(G)

(H)

(I)

(J)

(K)

Q 7. Which of the following resonating structure of 1

– methoxy – 1,3 – butadiene is least stable?

[IIT JEE 2005S]

(A) 2 3CH CH CH CH O CH−

− = − = −

(B) 2 3CH CH CH CH O CH−

= − − = −

(C) 2 3CH CH CH CH O CH−

− − = − −

(D) 2 3CH CH CH CH O CH−

= − = − −

Q 8. Resonance energy will be more if

(A) canonical structures are equivalent than if

canonical structures are non-equivalent.

(B) canonical structures have charge separation

than if canonical structures have no charge

separation.

(C) canonical structures have more charge

separation than if canonical structures have

less charge separation.

(D) molecule is aromatic than if molecule is not

aromatic.

Q 9. Which of the following statements is (are) true

about the contribution of a canonical structure in

resonance hybrid?

(A) more stable canonical structure will have

more contribution than less stable canonical

structures.

(B) A charge separated canonical structure will

have more contribution than a canonical

structures without charge separation.

(C) A canonical structures with –ve charge on

more electronegative atom and +ve charge

on less electronegative atom will have more

contribution than a canonical structure with

+ve charge on more electronegative atom and

–ve charge on less electronegative atom.

(D) A canonical structure with more number of

bonds will have more contribution than a

canonical structure with less number of bonds.

Q 10. Assertion (A): Energy of resonance hybrid is

equal to the average of energies of all canonical

structure.

Reason (R): Resonance hybrid can’t be presented

by a single structure. [NCERT Examaplar]

(A) Both A & R are correct and R is the correct

explanation of A

(B) Both A & R is correct but R is not correct

explanation of A

(C) Both A & R are not correct

(D) A is not correct but R is correct

Q 11. Which of the following resonating structure is the

minor contribution to the real structure?

N N

CH2 CH2

R P = O 3 R P – O 3

CH 2 CH 2

C

O

H

NH

H

C

O

H

NH

O

C

CH 2 H

O

C

CH 2 H

CH – O – CH 2 3 CH =O – CH 2 3

CH – CH = CH – O 3 CH – CH – CH = O 3

CH – C = CH2 2 CH = C – CH2 2




34

(A) I (B) II

(C) III (D) All of these

Q 12. Which of the following compound has both the

resonating structure contributing equal to the

resonance hybrid?

(A)

(B)

(C)

(D)

Q 13. Which of the following pairs has higher

resonance energy?

(A) CH3 COOH and CH3COONa

(B) CH2=CH-O– and CH2=CH-OH

(C)

(D)

(E) CH3 COCl and CH3 COF

(F) CH2=CH-F and CH2=CH-Br

(G)

(H)

(I)

(J)

(K)

(L)

(M)

(N) CH2=CH-OH and CH2=CH-CH=CH-OH

(O)

(P) CH2=CH-O-CH=CH2 &

CH2=CH-NH-CH=CH2

(Q) CH2=CH-NH and HN=CH-NH

(R)

Q 14. Which of the following statements is true about

the contribution of I and II in respective

resonance hybrid?

(A) Both I and II have same contributions

(B) I has more contribution than II

(C) I has less contribution than II

(D) It is not possible to analyse their relative

contribution.

Q 15. Among these molecules, the correct order of

resonance energy per ring is

(A) III>II>I (B) I>II>III

(C) I>II>III (D) II>I>III

CH = CH – CH = O CH – CH = CH – O2 2

COO

and

O

and

And CH = CH – CH2 2



And

OH

OH

And

And

O

And

O

And

N

AndN

H

CH = CH – O CH2 3CH – CH = O CH2 3

I

CH = CH – NH CH2 3CH – CH = NH CH2 3

II




35

6. Effects of Resonance on Bond Length

Q 1. Among these compounds, the correct order of

C-N bond lengths is

(A) 4 >1 > 2 > 3 (B) 3 > 1 > 2 > 4

(C) 3 > 2 > 1 > 4 (D) 3 > 1 > 4 > 2

Q 2. Which of the following is the correct order of

C-C bond lengths among these compounds?

CH3O-CH=CH-NO2 I

CH2=CH-NO2 II

CH2=CH-OCH3 III

CH2=CH2 IV

(A) I > II > III > IV (B) IV > III > II > I

(C) I > III > II > IV (D) II > III > I > IV

Q 3. Which of the following statements would be true

about this compound?

(A) All three C-N bonds are of same length .

(B) Cl-N and C3-N bonds are of same length but

shorter than C5-N bond.

(C) Cl-N and C3-N bonds are of same length but

longer than C5-N bond.

(D) Cl-N and C3-N bonds are of different lengths

but both are longer than C5-N bond.

Q 4. In which of the given compound C-O bond length

is minimum?

(A) (B)

(C) (D)

Q 5. The correct order of increasing C-O bond length

of 23 2CO,CO ,CO−

is

(A) 23 2CO CO CO− (B) 2

2 3CO CO CO−

(C)23 2CO CO CO− (D) 2

2 3CO CO CO −

Q 6. In which of the following mulecule resonance is

isovalent?

(A) (B) CH2=CH-CH=CH2

(C) (D). None of these Q 7. In which of the following molecules – electron

density in ring is minimum?

(A) (B)

(C) (D)

Q 8. In which of the following molecules – electron

density in ring is maximum?

(A) (B)

(C) (D)

Q 9. In Pyrole

[NEET 2016 – II]

NH2

CHO

I

NH2

II

NH2

CH = NH2

III IV

13

5

O N2

BrNO2

NO2

HO

OH

OH

NH2

OH

HC OO

CHO

NO2 OCH3

NO2

H N2

NO2 O

NH2 OCH3

N

H

NO 2

NO 2




36

The electron density is maximum on

(A) 2 & 3 (B) 3 & 4

(C) 2 & 4 (D) 2 & 5

Q 10. Following are the canonical structures of

naphthalene

Which of the following statements is true about

the Cl-C2 and C2-C3 bond lengths?

(A) Both bonds are of same length.

(B) Cl-C2 bond is longer than C2-C3 bond.

(C) Cl-C2 bond is shorter than C2-C3 bond.

(D) It is not possible to judge the bond lengths

because given structures are tautomers


this molecule?

2

3

4

1

(A) C1-C2 and C3-C4 bonds are of same length.

(B) C1-C2 bond is shorter than C3-C4 bond.

(C) C1-C2 bond is longer than C3-C4 bond.

(D) C1-C2 and C2-C3 bonds are of same length.

Q 12. The order of the C-O bond lengths among these

compounds is

NO2

OHOHOH

NO2I II III

(A) I > II > III (B) III > II > I

(C) II > I > III (D) III > I > II

Q 13. Which of the following compounds do not have

all C-C bonds of same length?

A)

B)

+C)

_D)

Q 14. Among the following compounds which has

longer C-O bonds?

O

CH HA)

O

CHB) F O

CHC) NH2

O

CHD) OH Q 15. In the anion HCOO – the two carbon – oxygen

Bonds are formed of equal length. What is the

reason for it. [AIEEE 2003]

(A) The C=O bond is weaker than C – O bond

(B) The anion HCOO– has 2 resonating structure.

(C) The anion is obtained by removal of a proton

from the acid molecule

(D) Electronic orbitals of carbon atom are

hybridiesed

7. Resonance Energy, Effect of Resonance

Q 1. The stability order of these canonical structures is

(A) I > II > III (B) II > III > I

(C) I > III > II (D) III > I > II

Q 2. The most stable canonical structures of this

molecule is

(A) (B)

(C) (D)

12

34

2

3

1

4

2

3

1

CH – C – N3

OHCH3

CH3

CH – C – N3

OHCH3

CH3

CH – C – N3

OHCH3

CH3

I II III

N

N

N

N

N

N

N

N

N

N




37

Q 3. Among the following, the least stable resonance

structures is

(A)

(B)

(C)

(D)

Q 4. Which of the following canonical structures is

least stable?

(A) I (B) II

(C) III (D) both II&III.

Q 5. The correct stability order of the following

resonance structure is

(I) 2H C N N+ −

= = (II) 2H C N N+ −

− =

(III) 2H C N N− +

− (IV) 2H C N N− +

− =

(A) I II IV III (B) I III II IV

(C) II I III IV (D) III I IV II

Q 6. A highly important canonical structure of this

molecule is

(A) (B)

(C) (D)

Q 7. Which of the following pairs of compounds has

greater resonance energy?

(A)

(B)

(C) (D)

Q 8. Resonance energies of these cations are in the

order

(A) II > I > III (B) I > II > III

(C) III > II > I (D) III > I > II

Q 9. Resonance energies of these compounds are in

the order as

N = O

O

N = O

O

N = O

O

N – O

O

N|

H I

N|

HII

N|

H

III

O

O

O

O

OI

II

Or

N|

H

O Or O

Or

CH2

N|

HI

II III

O

Or

CH 2 +

O




38

(A) I > III > II (B) III > II > I


Q 10. Among these compounds what is the order of the

resonance energies?

(A) III > IV > I > II (B) III > IV > II > I

(C) II > I > IV > III (D) I > II > IV > III

Q 11. Which of the following choice is the correct order

of resonance energy of these molecule?

(A) I > II > III (B) III > II > I


Q 12. Which of the following choice is the order of

resonance energy of these radicals?

(A) I > II > III (B) I > III > II

(C) III >I > II (D) III > II > I

Q 13. In the following molecule, the correct order of

heat of hydrogenation is

(A) IV III II I (B) IV III II I

(C) II IV I III (D) II IV III I

Q 14. Heat of hydrogenation.

(I) -28.6 k cal/mole

(II) -55.5k cal/mole

(III)-49.8k cal/mole

As shown above, heat of hydrogenation of II is

more than that of I. But heat of Hydrogenation of

III is less than that of II. Suggest a suitable

explanation. Based on these Heats of

hydrogenation what will be the correct order of

their stability:

(A) I > II > III (B) II > I > III

(C) II > III > I (D) I > III > II

Q 15. Among the following pairs identify the one which

gives higher heat of hyderogenation?

(A)

(B)

(C) 2 2CH CH CH CH= − = and

3 3CH CH CH CH− = −

(D)

(E)

(F)

Q 16. In which of the following pairs, indicated bond is

of greater strength?

(A)

(B)

(C)

(D)

OH

I II III

N

I II IIIIV

I II III

I

CH2

CH = CH – CH2 2

II

CH = CH – CH – CH = CH2 2

III

OCH3 OCH3

I II

OCH3 OCH3

III IV

CH2CH3

CH2

And

CH2CH3

CH3

CH2CH3

CH3

And

CH2CH3

CH3

C = C CH3

H

H

CH3

And C = C CH3

H H

CH3

CH = CH – CH2

CH3

CH3

And CH = C2

CH3

CH – CH2 3

CH2

CH2

And

CH3

CH2

C

O

CH3

C1

And CH – CH – C13 2

CH C – C CH and CH = CH – CH = CH 2 2

CH – C CH and HC CH3

C

O

H N2 NH2

AndC

O

CH3 NH2




39

(E)

8. Introduction to Aromaticity

Q 1. Select the compounds/ions which are aromatic

anti-aromatic and non –aromatic seperately

1. 2. 3.

4. 5. 6.

7. 8. 9.

10. 11. 12.

13. 14. 15.

16. 17.

18. 19. 20.

21. 22.

23. 24.

25. 26.

27. 28.

29. 30.

31. 32.

33. 34.

Q 2. Which of the given is most stable carbonium ion

(A) (B)

(C) (D)

Q 3. Which of the given is most stable carbanion

(A) (B)

(C) (D)

Q 4. The most polar compound is

(A) (B)

(C) (D)

Q 5. Which of the given is not polar

N

O

O

N|

H O

O

NH

O

BO

B

OB

CH3

H C3 CH3

S

O

HN

H–B

B – CH3

B – CH3

O SiH

HH C–B3 Si

H

H

S

N: N:

N:

CH2

CH2

CH

CH 2 CH 3

And




40

(A) (B)

(C) (D)

Q 6. Rotation about indicated bonds is easiest in which

of these molecules?

(A) I (B) II (C) III (D) IV

Q 7. In which of the given axial rotation barrier along

C C= between two rings follows the correct

order is

(I) (II) (III)

(A) I II III (B) II III I

(C) III I II (D) II I III

Q 8. Total number of delocalized electrons in the

given compound is

(A) 16 (B) 12

(C) 18 (D) 20

Q 9. Which of the following is a non – aromatic

compound / species?

(A) (B)

(C) (D)

(A) A (B) B

(C) C (D) D

Q 10. The compound which cannot rearranged into an

aromatic compound is

(A) (B)

(C) (D)

Q 11. For the benzyne correct statement is

(A) Four carbon atom is 2sp and 2 carbon

atom is sp hybridized

(B) All the carbon is sp hybridized

(C) All the carbon is 2sp hybridized

(D) None of these

Q 12. For the benzyne correct statement is

(A) the Pi bond formed outside the ring between

P orbitals

(B) The pi bond formed outside the ring is in

between SP2 orbitals

(C) 2 carbon atoms are SP Hybridised

(D) None of these

Q 13. Stability order of these compounds is in the order

(A) I > II > III (B) I > III > II

(C) III > I > II (D) II > I > III

Q 14. Which of the following compounds is not

aromatic?

Q 15. The correct stability order of the given molecule

is

I

II CH2 = CH2

III

HC CH

IV

N:

O: :

NH:

N

:




41

(A) II III I IV (B) II III IV I

(C) I II III IV (D) II I III IV

9. Aromatisation Reaction & U.F. Factor

Q 1. Which produces aromatic species in each of the

following reactions?

(A)

(B)

(C)

(D)

(E)

(F)

Q 2. The ease of ionization of these compounds to

produce Br is in the order as:

(A) I > II > III (B) III > I > II

(C) II > III > I (D) III > II > I

Q 3. The order of the ease of ionization of these

compounds to produce carbocations and Br– is

(A) I > III > II (B) II > I > III

(C) I > III > II (D) III > II > I

Q 4. Ease of ionization to produce carbocation and

Bromide will be maximum in which of the

following compounds

(A) (B)

(C) (D)


this molecule (furan))?

(A) Both lone-pair of electrons are in sp3 orbitals.

(B) Both lone-pair of electrons are in sp2 orbitals.

(C) Both lone-pair of electrons are in Pz orbitals.

(D) One lone pair of electrons in sp2 orbital while the

other is in Pz.

Q 6. Lone pair of pyridine (C6H5N), is in

(A) p- orbital (B) sp3- orbital

(C) sp2- orbital (D) sp- orbital

Q 7. Calculate hydrogen deficiency index

(unsaturation factor) in each of the following

molecular Formula

(A) C14H12N2O2Cl2 (B) C2H8N2

(C) CH3 radical (D) (C3H5)

(E) (C5H5) (F) (C7H8NO)

(G) C6H5Cl (H) C2HO2Na

Q 8. What is the unsaturation factor in each of the

following compounds?

(A) 3CH CN (B) 3CH COOH

(C) (D)

(E) (F)

(G)

III IV

K?

HClO4?

Na?

CH2

O

NaH?

O Br O

I II

Br N

CH3

Br

III

H

I BrH

II

H

III

Br

BrBr

Br

CH O3 Br

O

::

CHO

Buli ?

O HClO 4

?

I II




42

Q 9. If unsaturation factor of a molecule is 2. If

implies that molecule has

(A) two dausle bonds (B) one triple bond

(C) two cyclic structure (D) All of these

Q 10. Unsaturation factor can’t have

(A) fractional value (B) zero value

(C) –ve value (D) All are possible

Q 11. Find no of hemolytic cyclic structure possible

from the formula 4 8C H O

(A) 4 (B) 5

(C) 6 (D) 3

Q 12. Find number of carbonyl compounds possible

from the molecular formula 4 8C H O

(A) 3 (B) 4

(C) 5 (D) 6

Q 13. Find number of structural isomers possible from

molecules formula 4 8C H

(A) 4 (B) 6

(C) 8 (D) 5

Q 14. Find number of two cyclic structures possible

from molecular formula 5 8C H

(A) 4 (C) 3

(C) 5 (D) 6

Q 15. Find number of Amide structure possible from

the molecular formula 4 9C H NO

(A) 6 (B) 8

(C) 10 (D) 5

Q 16. Find the number of benzene ring structure

possible from the molecular formula 9 12C H

(A) 8 (B) 7

(C) 6 (D) 10

Answer Key 1. Hybridisation in Organic Chemistry

(1). B (2). C (3). D

(4). C (5). D (6). A

(7). B (8). D (9). D

(10). B (11). B (12). A

(13). C (14). A (15). C

(16). D (17). B (18). C

(19). D (20). C

2. Characteristics of Hybridisation

(1). A (2). C (3). C

(4). D (5). B (6). D

(7). C (8). C (9). C

(10). D (11). A (12). B

(13). A (14). C (15). C

(16). B (17). A




43

(18).

No of Pi Bonds Hybridisation of C, N & O

0 SP3

1 SP2

2 SP

(19). A, E, F, I, K (20). A, B, D, E, I, J, K

(21). 18, 6, 42, 3, 15, 12

3. Resonance

(1). D (2). A, B, D (3). B

(4). D (5). B (6). D

(7). B (8). B

(9). D, G, H, I, J

(10). See the Notes

(11). Donar – B, C, E, F, G, H, I, J

Acceptor – A, B, C, D, F, G, H, I, J

(12). A, B, C, E +ve charge Only, G, I J, N

(13). C

4. Drawing Resonating Structure

(1). A (2). A (3). B

(4). D (5). D (6). C

(7). C (8). D (9). D

(10). D (11). C (12). B

(13). B (14). A

5. Stability of Resonating Structures

(1). A, B, D (2). A (3). A

(4). A (5). C

(6). A – 1, B – Equal, C – 1. D – 1, E – 1, F – 2,

G – 2, H – 1, I – 1, J – 2, K – 2

(7). C (8). A, D (9). A, C, D

(10). D (11). B (12). C

(13). A – 2, B – 1, C – 2, D – 2, E – 2, F -1, G –

2, H – 2, I -1, J – 2, K – 2, L – 1, M – 2, N – 2, O

-2, P – 2, Q – 2, R – 2

(14). C (15). C

6. Effects of Resonance on Bond Length

(1). C (2). A (3). C

(4). C (5). D (6). A

(7). D (8). B (9). D

(10). C (11). B (12). B

(13). B (14). C (15). D

7. Resonance Energy, Effect of Resonance

(1). D (2). A (3). B

(4). B (5). B (6). B

(7). A – II, B – I , C – I , D – I

(8). A (9). D (10). B

(11). A (12). B

(13). C (14). D

(15). A – I, B – I, C – I, D – I

(16). A – 1, B – I, C – 2, D – 2, E – 2

8. Introduction to Aromaticity

(1). Aromatic : 1, 2, 3, 5, 7, 8, 9, 11, 14, 15, 16,

17, 18, 21, 22, 25, 27, 31, 32, 33, 34

Non-aromatic : 4, 6, 13, 19, 30

Anti – aromatic: 10, 12, 23, 24, 26, 28

(2). B (3). B (4). D

(5). A (6). A (7). D

(8). B (9). D (10). D

(11). C (12). B (13). A

(14). D (15). C

9. Aromatisation Reaction & U.F. Factor

(1). All (2). B (3). A

(4). A (5). D (6). C

(7). (A) 9 (B) 0 (C) 1/2 (D) 3/2

(E) 7/2 (F) 9/2 (G) 4 (H) 2

(8). A – 2, B – 1, C – 4, D – 2, E – 4, F – 5, G – 3

(9). D (10). C (11). B

(12). A (13). D (14). C

(15). B (16). A


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