Organic Chemistry – Some Basic Principles and Techniques

Consider the following compounds : [figure] Hyperconjugation occurs in

1. III only
2. I and III
3. I only
4. II only

The enolic form of ethyl acetoacetate as shown below has [figure]

1. 9 sigma bonds and 2 pi-bonds
2. 9 sigma bonds and 1 pi-bond
3. 18 sigma bonds and 2 pi-bonds
4. 16 sigma bonds and 1 pi-bond.

In which of the following compounds, the C–Cl bond ionisation shall give most stable carbonium ion?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Given : [figure] The enthalpy of hydrogenation of these compounds will be in the order as

1. II > III > I
2. II > I > III
3. I > II > III
4. III > II > I

Which of the following organic compounds has same hybridization as its combustion product (CO2)?

1. Ethane
2. Ethyne
3. Ethene
4. Ethanol

The radical, [figure] is aromatic because it has

1. 7 p-orbitals and 7 unpaired electrons
2. 6 p-orbitals and 7 unpaired electrons
3. 6 p-orbitals and 6 unpaired electrons
4. 7 p-orbitals and 6 unpaired electrons.

The structure of isobutyl group in an organic compound is

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Structure of the compound whose IUPAC name is 3-Ethyl-2-hydroxy-4-methylhex-3-en-5-ynoic acid is

1. [figure]
2. [figure]
3. [figure]
4. [figure]

The outer orbitals of C in ethene molecule can be considered to be hybridized to give three equivalent sp2 orbitals. The total number of sigma (σ) and pi (π) bonds in ethene molecule is

1. 3 sigma (σ) and 2 pi (π) bonds
2. 4 sigma (σ) and 1 pi (π) bonds
3. 5 sigma (σ) and 1 pi (π) bonds
4. 1 sigma (σ) and 2 pi (π) bonds

Arrange the following in increasing order of stability 1. (CH3)2- C-CH2-CH3 2. (CH3)3- C 3. (CH3)2- CH 4. CH3- CH2 5. CH3

1. 5 < 4 < 3 < 1 < 2
2. 4 < 5 < 3 < 1 < 2
3. 1 < 5 < 4 < 3 < 2
4. 5 < 4 < 3 < 2 < 1

What is the hybridisation state of benzyl carbonium ion? [figure]

1. sp2
2. spd2
3. sp2d
4. sp3

Homolytic fission of the following alkanes forms free radicals CH3-CH3, CH3-CH2-CH3, (CH3)2CH-CH3, CH3-CH2-CH(CH3)2. Increasing order of stability of the radicals is

1. (CH3)2 C-CH2CH3 < CH3- CH-CH3 < CH3- CH2 < (CH3)3 C
2. CH3- CH2 < CH3- CH-CH3 < (CH3)2 C-CH2-CH3 < (CH3)3 C
3. CH3- CH2 < CH3- CH-CH3 < (CH3)3 C < (CH3)2 C-CH2CH3
4. (CH3)3 C < (CH3)2 C-CH2CH3 < CH3- CH-CH3 < CH3- CH2

Which of the following chemical system is non aromatic?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Which nomenclature is not according to IUPAC system?

1. Br-CH2-CH=CH2 1-Bromoprop-2-ene
2. [figure] 4-Bromo-2,4-dimethylhexane
3. [figure] 2-Methyl-3-phenylpentane
4. [figure] 5-Oxohexanoic acid

Which one of the following is most reactive towards electrophilic reagent?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

The correct IUPAC name for the compound is [figure]

1. 4-ethyl-3-propylhex-1-ene
2. 3-ethyl-4-ethenylheptane
3. 3-ethyl-4-propylhex-5-ene
4. 3-(1-ethylpropyl)hex-1-ene

Which of the following species is not electrophilic in nature?

1. Cl
2. BH3
3. H3 O
4. NO2

The IUPAC name of the compound CH3CH=CHC CH is

1. pent-4-yn-2-ene
2. pent-3-en-1-yne
3. pent-2-en-4-yne
4. pent-1-yn-3-ene

Which one of the following is most reactive towards electrophilic reagent?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

The IUPAC name of the compound having the formula CH C-CH=CH2 is

1. 1-butyne-3-ene
2. but-1-yne-3-ene
3. but-1-en-3-yne
4. 3-butene-1-yne.

The state of hybridisation of C2, C3, C5 and C6 of the hydrocarbon, [figure] is in the following sequence

1. sp3, sp2, sp2 and sp
2. sp, sp2, sp2 and sp3
3. sp, sp2, sp3 and sp2
4. sp, sp3, sp2 and sp3

Base strength of [figure] is in the order of

1. (i) > (iii) > (ii)
2. (i) > (ii) > (iii)
3. (ii) > (i) > (iii)
4. (iii) > (ii) > (i)

Which one of the following is most reactive towards electrophilic attack?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

The stability of carbanions in the following [figure] is in the order of

1. (iv) > (ii) > (iii) > (i)
2. (i) > (iii) > (ii) > (iv)
3. (i) > (ii) > (iii) > (iv)
4. (ii) > (iii) > (iv) > (i)

In the hydrocarbon, 6CH3- 5CH= 4CH- 3CH2- 2C 1CH The states of hybridization of carbons 1, 3 and 5 are in the following sequence

1. sp, sp2, sp3
2. sp3, sp2, sp
3. sp2, sp, sp3
4. sp, sp3, sp2

For (i) I-, (ii) Cl-, (iii) Br-, the increasing order of nucleophilicity would be

1. Cl- < Br- < I-
2. I- < Cl- < Br-
3. Br- < Cl- < I-
4. I- < Br- < Cl-

Consider the following compounds (i) C6H5COCl (ii) [figure] (iii) [figure] (iv) [figure] The correct decreasing order of their reactivity towards hydrolysis is

1. (i) > (ii) > (iii) > (iv)
2. (iv) > (ii) > (i) > (iii)
3. (ii) > (iv) > (i) > (iii)
4. (ii) > (iv) > (iii) > (i)

The general molecular formula, which represents the homologous series of alkanols is

1. CnH2nO
2. CnH2nO2
3. CnH2n+2O
4. CnH2n+1O

The IUPAC name of [figure] is

1. 1-chloro-1-oxo-2, 3-dimethylpentane
2. 2-ethyl-3-methylbutanoyl chloride
3. 2, 3-dimethylpentanoyl chloride
4. 3, 4-dimethylpentanoyl chloride.

The general molecular formula, which represents the homologous series of alkanols is

1. CnH2n+2O
2. CnH2nO2
3. CnH2nO
4. CnH2n+1O