Match the intermediates given in Column I with their probable structure in Column II. Column I Column II (i) Free radical (a) Trigonal planar (ii) Carbocation (b) Pyramidal (iii) Carbanion (c) Linear

(i)Free radical-----(a)Trigonal planar Free radicals are formed as a result of homolytic fission of covalent bond and C becomes sp 2 hybridised. Shape of free radical is trigonal planar. (ii)Carbocation-----(a)Trigonal planar In carbocation, positively charged C is sp 2 hybridised and shape is trigonal planar. (iii)Carbanion-----(b)Pyramidal In carbanion, negatively charged C is sp 3 hybridised with lone pair and shape is pyramidal. (i) → (a); (ii) → (a); (iii) → (b) Column I Column II (i) Free radical (a) Trigonal planar (ii) Carbocation (a) Trigonal planar (iii) Carbanion (b) Pyramidal

Match the ions given in Column I with their nature-given in Column II. Column I Column II (i) (a) Stable due to resonance (ii) F 3 - C ⊕ (b) Destabilised due to inductive effect (iii) (c) Stabilised by hyperconjugation (iv) CH 3 - C ⊕ H - CH 3 (d) A secondary carbocation

(i) (a) (b) (d) Stable due to resonance Destabilised due to inductive effect A secondary carbocation In a secondary ( 2 ° ) carbocation, the carbon with the positive charge is attached to two other alkyl groups, which may be the same or different. Through resonance the positive charge is dispersed over neighbouring carbon atoms, making the species carrying the charge more stable. Moreover, a secondary carbocation is destabilised by the inductive effect of electron withdrawing groups (-I effect). Electron-withdrawing groups have the tendency to withdraw electrons or pull electrons towards itself. Hence, these make the carbocation more electron deficient and destabilise the cation. (ii) F 3 - C ⊕ (b) Destabilised due to inductive effect When an electronegative atom, such as a halogen, is introduced to a chain of atoms (generally carbon atoms), the resulting unequal sharing of electrons generates a positive charge which is transmitted through the chain. This causes a permanent dipole to arise in the molecule wherein the electronegative atom holds a negative charge and the carbon atom holds a positive charge, resulting in the formation of a carbocation. The corresponding effect is called the electron-withdrawing inductive effect, or the -I effect. (iii) (b) Destabilised due to inductive effect When a chemical species with the tendency to release or donate electrons, such as an alkyl group, is introduced to a carbon chain, the charge is relayed through the chain. These electron-donating groups increases the electron density over the carbanion making it more unstable. This effect is called the positive inductive effect or the +I Effect. (iv) CH 3 - C ⊕ H - CH 3 (c) (d) Stabilised by hyperconjugation A secondary carbocation In a secondary ( 2 ° ) carbocation, the carbon with the positive charge is attached to two other alkyl groups, which may be the same or different. Hyperconjugation stabilises the carbocation as it helps in the dispersal of positive charges. Thus, we can say that the greater the number of alkyl groups attached to a positively charged carbon atom, the greater is the hyperconjugation interaction and stabilisation of the carbocation. Column I Column II (i) (a) (b) (d) Stable due to resonance Destabilised due to inductive effect A secondary carbocation (ii) F 3 - C ⊕ (b) Destabilised due to inductive effect (iii) (b) Destabilised due to inductive effect (iv) <img alt="" src="<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>CH</mi><mn>3</mn></msub><mo>-</mo><mover><mi mathvariant="normal">C</mi><mo>⊕</mo></mover><mi mathvariant="normal">H</mi><mo>-</mo><msub><mi>CH</mi><mn>3</mn></msub></math>" /> CH 3 - C ⊕ H - CH 3 (c) (d) Destabilised due to inductive effect A secondary carbocation

What is meant by hybridisation? Compound CH 2 = C = CH 2 contains sp or sp 2 hybridised carbon atoms. Will it be a planar molecule?

Hybridisation is defined as the concept of mixing two atomic orbitals with the same energy levels to give a new set of equivalent orbitals known as hybrid orbitals which are used in bond formation. This phenomenon is known as hybridisation. The properties and energy of the new, hybridised orbital are an 'average' of the original unhybridised orbitals. In CH 2 = C = CH 2 (allene), terminal carbon atoms are sp 2 hybridised as each one has 3 σ bonds while second carbon atom has 2 σ bonds and is sp hybridised. Allene molecule as a whole is non-planar in nature.

MEDIUM

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IMPORTANT

Earn 100

Match Column I with Column II.

Column I Column II

(i) Dumas method (a) ${AgNO}_{3}$

(ii) Kjeldahl's method (b) Silica gel

(iii) Carius method (c) Nitrogen gas

(iv) Chromatography (d) Free radicals

(v) Homolysis (e) Ammonium sulphate

Important Questions on Organic Chemistry – Some Basic Principles and Techniques

MEDIUM

11th CBSE

IMPORTANT

NCERT Exemplar Chemistry - Class 11>Chapter 12 - Organic Chemistry – Some Basic Principles and Techniques>Matching Type>Q 53

Match the intermediates given in Column I with their probable structure in Column II.

	Column I		Column II
(i)	Free radical	(a)	Trigonal planar
(ii)	Carbocation	(b)	Pyramidal
(iii)	Carbanion	(c)	Linear

HARD

11th CBSE

IMPORTANT

NCERT Exemplar Chemistry - Class 11>Chapter 12 - Organic Chemistry – Some Basic Principles and Techniques>Matching Type>Q 54

Match the ions given in Column I with their nature-given in Column II.

	Column I		Column II
(i)		(a)	Stable due to resonance
(ii)	$F_{3} - \overset{\oplus}{C}$	(b)	Destabilised due to inductive effect
(iii)		(c)	Stabilised by hyperconjugation
(iv)	${CH}_{3} - \overset{\oplus}{C} H - {CH}_{3}$	(d)	A secondary carbocation

HARD

11th CBSE

IMPORTANT

NCERT Exemplar Chemistry - Class 11>Chapter 12 - Organic Chemistry – Some Basic Principles and Techniques>Long Answer Type>Q 61

What is meant by hybridisation? Compound

{CH}_{2} = C = {CH}_{2}

contains

sp

{sp}^{2}

hybridised carbon atoms. Will it be a planar molecule?

HARD

11th CBSE

IMPORTANT

NCERT Exemplar Chemistry - Class 11>Chapter 12 - Organic Chemistry – Some Basic Principles and Techniques>Long Answer Type>Q 62

Benzoic acid is an organic compound. Its crude sample can be purified by crystallisation from hot water. What characteristic differences in the properties of benzoic acid and the impurity make this process of purification suitable?

HARD

11th CBSE

IMPORTANT

NCERT Exemplar Chemistry - Class 11>Chapter 12 - Organic Chemistry – Some Basic Principles and Techniques>Long Answer Type>Q 63

Two liquids

(A) and (B)

can be separated by the method of fractional distillation. The boiling point of a liquid

(A)

is less than the boiling point of a liquid

(B)

. Which of the liquids do you expect to come out first in the distillate? Explain.

HARD

11th CBSE

IMPORTANT

NCERT Exemplar Chemistry - Class 11>Chapter 12 - Organic Chemistry – Some Basic Principles and Techniques>Long Answer Type>Q 64

You have a mixture of three liquids

A, B and C

. There is a large difference in the boiling points of

A

and rest of the two liquids i.e.,

B and C

. The boiling point of liquids

B and C

are quite close. Liquid

A

boils at a higher temperature than

B and C

and boiling point of

B

is lower than

C

. How will you separate the components of the mixture? Draw a diagram showing set up of the apparatus for the process.

HARD

11th CBSE

IMPORTANT

NCERT Exemplar Chemistry - Class 11>Chapter 12 - Organic Chemistry – Some Basic Principles and Techniques>Long Answer Type>Q 65

Draw a diagram of bubble plate type fractionating column. When do we require such type of column for separating two liquids? Explain the principle involved in the separation of components of a mixture of liquids by using a fractionating column. What industrial applications does this process have?

HARD

11th CBSE

IMPORTANT

NCERT Exemplar Chemistry - Class 11>Chapter 12 - Organic Chemistry – Some Basic Principles and Techniques>Long Answer Type>Q 66

A liquid with high boiling point decomposes on simple distillation but it can be steam distilled for its purification. Explain how is it possible?

	Column I		Column II
(i)	Dumas method	(a)	${AgNO}_{3}$
(ii)	Kjeldahl's method	(b)	Silica gel
(iii)	Carius method	(c)	Nitrogen gas
(iv)	Chromatography	(d)	Free radicals
(v)	Homolysis	(e)	Ammonium sulphate

Match Column I with Column II. Column I Column II (i) Dumas method (a) AgNO3 (ii) Kjeldahl's method (b) Silica gel (iii) Carius method (c) Nitrogen gas (iv) Chromatography (d) Free radicals (v) Homolysis (e) Ammonium sulphate

Important Questions on Organic Chemistry – Some Basic Principles and Techniques

Learn and Prepare for any exam you want !

Match Column I with Column II.

Column I Column II

(i) Dumas method (a) ${AgNO}_{3}$

(ii) Kjeldahl's method (b) Silica gel

(iii) Carius method (c) Nitrogen gas

(iv) Chromatography (d) Free radicals

(v) Homolysis (e) Ammonium sulphate