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

Question # 1

Write down nitration and sulphonation of benzene?

Ans 1: The introduction of NO₂group in benzene ring is called Nitration,.The nitration of benzene takes place when it is heated with a 1:1 mixture of conc.HNO₃and conc.Sulphuric at 50-55 degree acid reacts with nitrir acid to generate nitronium ion.

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 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 # 4

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 # 5

What objective were raised on Kekule formula of Benzene?

Ans 1: Kekula formula with three double bonds demands of high degree of unsaturation from benzene while usually it exhibits a saturated character,This benzene yields substitution products readily and from addition products .Benzene is also very stable compound.

Question # 6

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 # 7

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 # 8

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

Ans 1: Benzene is extraordinary stable molecule,This stability is due to the extensive delocalization of pi electron.The unhybridized orbital partially overlap to form a continue sheath of electron cloud,enveloping above and below the six carbon carbon sigma bonds of the ring,

Question # 9

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 # 10

Define two reaction which show that Benzene is an unsaturated hydrocarbons?

Ans 1: Benzene is reduced to cyclohexane on heating at high temperature with hydrocarbons in the presence if Pt in an acidic solvent or Ni at 200 Degree as a catalyst,This reaction show that benzene is Un-saturated compound.

Halogenation: Benzene reacts with chlorine and bromine in the presence of sunlight to give addition products ,hexechlorobenezene or hexebromobenzene.

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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

Write down nitration and sulphonation of benzene?

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

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

Justify that Ethene is more reactive than C6H6.

What objective were raised on Kekule formula of Benzene?

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

What are monocyclic and polycyclic aromatic Hydrocarbons?

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

What is meant by directive influence of substituent?

Define two reaction which show that Benzene is an unsaturated hydrocarbons?

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

Write down nitration and sulphonation of benzene?

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

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

Justify that Ethene is more reactive than C6H6.

What objective were raised on Kekule formula of Benzene?

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

What are monocyclic and polycyclic aromatic Hydrocarbons?

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

What is meant by directive influence of substituent?

Define two reaction which show that Benzene is an unsaturated hydrocarbons?

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

Define two reaction which show that Benzene is an unsaturated hydrocarbons?

What is meant by directing group?

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

What is meant by directive influence of substituent?

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

Predict major product of bromination of nitrobenzene.

What is Wurtz -Fritting reaction?

Justify that Ethene is more reactive than C6H6.

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

Write down nitration and sulphonation of benzene?

12th Class Chemistry Chapter 9 Preparation

Justify that Ethene is more reactive than C₆H_6.

Justify that Ethene is more reactive than C₆H_6.

Justify that Ethene is more reactive than C₆H_6.