Find the 12th Class Fsc Chemistry Online Preparation chapter 9 ( Aromatic Hydrocarbons)

Question # 1

Define resonance energy?What is the resonance energy of benzene?

Ans 1: Benzene is more stable than the hypothetical 1,3,5-cyclohexatriene by 150.5 kj/mole.This difference between amount of heat is actually released and that calculated on the basis of the Kekule structure is called Resonance Energy Benzene shows the phenomenon of resonance which makes it more stable than others.In benzene electrons are delocalized making it a very stable molecule.The resonance energy of benzene is 150.5 kj/mole

Question # 2

What is meant by the terms:i) Aromatic ii) Oxidation

Ans 1: Aromatic:The term aromatic was derived from the Greek word aroma meaning fragrant and was used in organic chemistry for s special class of compounds.These compounds have low hydrogen to carbon ratio in their molecular formula and have a characteristic odour. These often produced by benzene or derivatives of benzene.
Ans 2: Oxidation:The addition of oxygen,removal of hydrogen or electrons is called oxidation.Oxidation process is carried out by some oxidizing agent like KMnO₄,K₂Cr₂O₇or V₂O₅etc.which can provide oxygen to a compound.

Question # 3

What is meant by directive influence of substituent?

Ans 1: When an electrophile substitution reaction take place on the benzene ring,we get only one monosubstituted benzene all the six position in the ring are equivalent .However introduction of second group into the ring may give three isomeric distributed products ,ortho,meta and para.

Question # 4

What is the general pattern of reactivity of benzene towards electrophone?

Ans 1: The highly stable delocalized electron of benzene ring not radley available for the nucleophilic attack like the electrons of alkenes.Therefore the electron of benzene ring do not assist in the attack of weal electrophiles,It means that more powerful electrophiles are required to penetrate and break the continuous sheath of electron cloud in benzene.

Question # 5

What information are obtained about structure of benzene from X-ray studies?

Ans 1: The X-ray studies of benzene have confirmed the hexagonal structure of it.These studies have also revealed that all the carbon and hydrogen atoms are in the same plane.All the angles are of 120^o.All C-C and C-H bonds lengths are 1.397 A^oand 1.09A^orespectively.

Question # 6

Predict major product of bromination of nitrobenzene.

Ans 1: m-bromonitrobenzene is the major product of bromination of nitrobenzene because nitro group on benzene is meta directing .

Question # 7

Justify that Ethene is more reactive than C₆H_6.

Ans 1: The highly sable ,delocalized electron of benzene ring not readily available for the nucleophilic attack like the electron of alkenes,therefore the electrons of benzune ring do not assist in the attack of weak electrophiles.

Question # 8

Why hydroxyl group in ortho and para directing?

Ans 1: Hydroxyl group release electron to the benzene ring .there by facilities the availability of electron to the electrophiles at ortho and para position.This result in the increase chemical reactivity of benzene ring towards electrophiles,The benzene ring can offer more than one position the new incoming group.

Question # 9

What are monocyclic and polycyclic aromatic Hydrocarbons?

Ans 1: Monocyclic: Aromatic hydrocarbons containing one benzene ring in their molecules are called monocyclic aromatic hydrocarbons e.g benzene,toluene phenol,aniline benzoic acid,benzaldehyde and benzene sulphonic acid.
Ans 2: Polycyclic:Aromatic hydrocarbons containing two or more benzene rings in their molecules are called monocyclic aromatic hydrocarbons.

Question # 10

What is resonance?

Ans 1: The possibility of different pairing schemes of valence electrons of atom is called resonance and the different thus arranged are called "Resonance Structure.".

Latest Educational News Stories

Pakistan's Largest Database of Colleges and Universities

BS Programs

University Past Papers

University Results

Exam Results 2024

Study Abroad Programs and Opportunities for Pakistani Students

12th Class Fsc Chemistry Online Preparation chapter 9 ( Aromatic Hydrocarbons)

Online Short Questions For Chapter 9 "12th Class Chemistry Chapter 9 Short Questions Preparation "

Chemistry - 12th Class Chemistry Chapter 9 Short Questions Preparation

Define resonance energy?What is the resonance energy of benzene?

What is meant by the terms:i) Aromatic ii) Oxidation

What is meant by directive influence of substituent?

What is the general pattern of reactivity of benzene towards electrophone?

What information are obtained about structure of benzene from X-ray studies?

Predict major product of bromination of nitrobenzene.

Justify that Ethene is more reactive than C6H6.

Why hydroxyl group in ortho and para directing?

What are monocyclic and polycyclic aromatic Hydrocarbons?

What is resonance?

Prepare Complete Set Wise Questions For Chapter 9 "12th Class Chemistry Chapter 9 Short Questions Preparation "

Set 1

Set 2

12th Class Chemistry Chapter 9 Short Questions Preparation - Set 1

Define resonance energy?What is the resonance energy of benzene?

What is meant by the terms:i) Aromatic ii) Oxidation

What is meant by directive influence of substituent?

What is the general pattern of reactivity of benzene towards electrophone?

What information are obtained about structure of benzene from X-ray studies?

Predict major product of bromination of nitrobenzene.

Justify that Ethene is more reactive than C6H6.

Why hydroxyl group in ortho and para directing?

What are monocyclic and polycyclic aromatic Hydrocarbons?

What is resonance?

12th Class Chemistry Chapter 9 Short Questions Preparation - Set 2

What are monocyclic and polycyclic aromatic Hydrocarbons?

What is resonance?

What objective were raised on Kekule formula of Benzene?

What information are obtained about structure of benzene from X-ray studies?

What is meant by directive influence of substituent?

What happens when Acidified KMnO4is added to Methyl Benzene and Ethylbenzene?

How benzene is converted into malic acid by catalytic oxidation?

What are aromatic hydrocarbons?Give two example.

What is meant by the terms:i) Aromatic ii) Oxidation

Why benzene is less reactive than alkenes although it has three pi bonds in it?

12th Class Chemistry Chapter 9 Preparation

Justify that Ethene is more reactive than C₆H_6.

Justify that Ethene is more reactive than C₆H_6.

What happens when Acidified KMnO₄is added to Methyl Benzene and Ethylbenzene?