2nd Year Chemistry Chapter 8 (Aliphatic Hydrocarbons) Online Preparation

Online Short Questions For Chapter 8 "12th Class Chemistry Chapter 8 Short Questions Preparation "

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Chemistry - 12th Class Chemistry Chapter 8 Short Questions Preparation

Question # 1

Why pie bond is more reactive than alpha bond?

Ans 1: In the formation of pie bond,the partially filled p-orbitals overlap in a parallel fashion,the probability of finding electron is thus away from the line joining the two nuclei,due to this reason pei electron are less fimely helf between the nuclei.

Question # 2

Define Ramy nickel.Give its use.

Ans 1: Rany nickel is a catalyst which is prepared by treating a Ni-Al alloy with caustic soda.Most alkanes are hydrogenated over Raney nickel at about 100 degree and upto 3-atmosphere pressure.

Question # 3

Describe nitration of methane.

Ans 1: It is substitution reaction of alkanes in which a hydrogen atom of an alkane is replaced by nitro group .Alkanes undergo vapour -phase nitration under dractic condition to give nitroalkanes.

Question # 4

Why are some hydrocarbons called saturated and other unsaturated?

Ans 1: Those compounds in which the four valencies of carbons are satisfied by single bonds to either other carbon atom or hydrogen atom are called saturated hydrocarbons,Those compounds in which the four valencies of carbon atom are not satisfied by single bonds,however satisfied by double or triple bond are called unsaturated hydrocarbons.

Question # 5

Define Hydrogenation,

Ans 1: Hydrogenation is a process in which molecule of hydrogen added to an alkene in the presence of a catalyst and at moderate pressure (1-5 atm ) to give a saturated compound.

Question # 6

Give three use of methane?

Ans 1:
- Methane is used as fuel as an illuminating gas.
- used for the preparation of methyl chloride ,methylene chloride,chloroform.
- for the preparation of carbon black used in paints ,prints printing inks and automobiles tyres.

Question # 7

Why ethene is more reactive than ethyne towards additions reactions?

Ans 1: Ethene contains sigma-bond having partially filled p-orbitals overlap in a parallel fashion.sigma-electrons are less firmly held between the nulei. In ethene a sigma-bond is a weak bond.
Ans 2: In ethyne,the carbon atoms are held together by a triple bond,a 0-bond and two sigma-bond.The electrons density between the carbon atoms is very high which draws atoms very close to each other.Electrons in a triple bond are,therefore,less exposed and thus less reactive reagents.

Question # 8

Explain acidic nature of ethyne?

Ans 1: Ethnelnethyne,the hydrogen atom is bonded to the carbon atom with sp-s overlap.The sp hybridized carbon atom of ethyne pulls the electrons more strongly making the attached hydrogen atom slightly acidic as:H-C=C^-8-H⁺⁸

Question # 9

What is effect of branching on boiling of alkanes?

Ans 1: The boiling points of alkanes having branced chain structure are lower than their isomeric normal chain alkanes,e.g n-butane has higher boiling point than isobutene.

Question # 10

How ethene can be prepared by Kolb's electrolysis?

Ans 1: When a concentrated solution of sodium or potassium of a monocarboxylic acid is electrolyzed an alkane is produced this method is only suitable foe the preparation of symmetrical alkanes.

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Prepare Complete Set Wise Questions For Chapter 8 "12th Class Chemistry Chapter 8 Short Questions Preparation "

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12th Class Chemistry Chapter 8 Short Questions Preparation - Set 1

Question # 1

Why pie bond is more reactive than alpha bond?

Ans 1: In the formation of pie bond,the partially filled p-orbitals overlap in a parallel fashion,the probability of finding electron is thus away from the line joining the two nuclei,due to this reason pei electron are less fimely helf between the nuclei.

Question # 2

Define Ramy nickel.Give its use.

Ans 1: Rany nickel is a catalyst which is prepared by treating a Ni-Al alloy with caustic soda.Most alkanes are hydrogenated over Raney nickel at about 100 degree and upto 3-atmosphere pressure.

Question # 3

Describe nitration of methane.

Ans 1: It is substitution reaction of alkanes in which a hydrogen atom of an alkane is replaced by nitro group .Alkanes undergo vapour -phase nitration under dractic condition to give nitroalkanes.

Question # 4

Why are some hydrocarbons called saturated and other unsaturated?

Ans 1: Those compounds in which the four valencies of carbons are satisfied by single bonds to either other carbon atom or hydrogen atom are called saturated hydrocarbons,Those compounds in which the four valencies of carbon atom are not satisfied by single bonds,however satisfied by double or triple bond are called unsaturated hydrocarbons.

Question # 5

Define Hydrogenation,

Ans 1: Hydrogenation is a process in which molecule of hydrogen added to an alkene in the presence of a catalyst and at moderate pressure (1-5 atm ) to give a saturated compound.

Question # 6

Give three use of methane?

Ans 1:
- Methane is used as fuel as an illuminating gas.
- used for the preparation of methyl chloride ,methylene chloride,chloroform.
- for the preparation of carbon black used in paints ,prints printing inks and automobiles tyres.

Question # 7

Why ethene is more reactive than ethyne towards additions reactions?

Ans 1: Ethene contains sigma-bond having partially filled p-orbitals overlap in a parallel fashion.sigma-electrons are less firmly held between the nulei. In ethene a sigma-bond is a weak bond.
Ans 2: In ethyne,the carbon atoms are held together by a triple bond,a 0-bond and two sigma-bond.The electrons density between the carbon atoms is very high which draws atoms very close to each other.Electrons in a triple bond are,therefore,less exposed and thus less reactive reagents.

Question # 8

Explain acidic nature of ethyne?

Ans 1: Ethnelnethyne,the hydrogen atom is bonded to the carbon atom with sp-s overlap.The sp hybridized carbon atom of ethyne pulls the electrons more strongly making the attached hydrogen atom slightly acidic as:H-C=C^-8-H⁺⁸

Question # 9

What is effect of branching on boiling of alkanes?

Ans 1: The boiling points of alkanes having branced chain structure are lower than their isomeric normal chain alkanes,e.g n-butane has higher boiling point than isobutene.

Question # 10

How ethene can be prepared by Kolb's electrolysis?

Ans 1: When a concentrated solution of sodium or potassium of a monocarboxylic acid is electrolyzed an alkane is produced this method is only suitable foe the preparation of symmetrical alkanes.

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12th Class Chemistry Chapter 8 Short Questions Preparation - Set 2

Question # 1

Why are alkenes also called olefins?

Ans 1: Alkenes also known as olefins(derived from Latin word olefiant meaning oil forming ) because its lower members from oily products on treatment with chlorine or bromine.

Question # 2

How common name of alkenes are derived?Give common names of CH₂=CH₂and CH₃-CH₂=CH_2?

Ans 1: For alkanes the word is derived from the Greek or Latin numerals indicating the number of carbons atom in molecule and the name is completed by adding ane as a suffix.Alkenes are similarly named by replacing the ending "ane" of the name of alkane with "ylene".

Question # 3

The sigma bonds are inert in alkanes.Explain?

Ans 1: In the alpha bond the electrons are very tightly held between the nuclei which make it very stable bond,A lot of energy is required to break it.The alkanes or paraffins under ordinary condition are inert towards acid,alkalis,oxidizing and reducing agents.

Question # 4

Identify the actual product ,when HBr is added to propene.

Ans 1: Propene is an unsymmetrical alkene,According to Markovnikov rule.the negative part of the adding reagent goes to that carbon,constituting the double bond,which has least number of hydrogen atom.

Question # 5

Why Alkynes are less reactive than alkenes towards Electrophilic Regents?

Ans 1: A sigma-bond in alkenes is not only weak but its electrons are more expose to an attack by an electrophilic reagent.Both these acts make the alkenes a very reactive class of compounds. Alkynes although contain two sigma-bond are less reactive than alkenes towards electrophilic reagents this is because the bond distance between the two triple bonded carbon atoms is very short and hence the sigma-electrons are not available to be attacked by electrophilic reagents.

Question # 6

Why are some hydrocarbons called saturated and other unsaturated?

Ans 1: Those compounds in which the four valencies of carbons are satisfied by single bonds to either other carbon atom or hydrogen atom are called saturated hydrocarbons,Those compounds in which the four valencies of carbon atom are not satisfied by single bonds,however satisfied by double or triple bond are called unsaturated hydrocarbons.

Question # 7

Write structural formulas for two compound;i) Vinyl acetylene ii) But-3-en-yne

Ans 1: i) Vinyl acetylene: CH₂=CH-C=CH
Ans 2: ii) 1-Butene-3-yne: CH₂=CH-C=CH

Question # 8

Alkanes are less reactive than alkenes. Comment?

Ans 1: The alkanes or paraffins(Latin: parum=little,affins=affinity) under ordinary condition are inert towards acids,alkalis,oxidizing and reducing agents.The un-reactivity of alkanes can also be explained on the basis of inertness of a o-bond.In a o-bond the electrons are very tightly held between the nuclei which makes it is very stable bond.A lot of energy is required to break it.
Ans 2: On the other hand alkenes contains sigma-bond,having partially filled p-orbitals overlap in a parallel fashion.sigma-electron are less firmly held between the nulei. In alkenes a sigma-bond is,therefore,a weak bond as compared to a o-bond.

Question # 9

Why pie bond is more reactive than alpha bond?

Ans 1: In the formation of pie bond,the partially filled p-orbitals overlap in a parallel fashion,the probability of finding electron is thus away from the line joining the two nuclei,due to this reason pei electron are less fimely helf between the nuclei.

Question # 10

Explain acidic nature of ethyne?

Ans 1: Ethnelnethyne,the hydrogen atom is bonded to the carbon atom with sp-s overlap.The sp hybridized carbon atom of ethyne pulls the electrons more strongly making the attached hydrogen atom slightly acidic as:H-C=C^-8-H⁺⁸

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12th Class Chemistry Chapter 8 Preparation

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2nd Year Chemistry Chapter 8 (Aliphatic Hydrocarbons) Online Preparation

Online Short Questions For Chapter 8 "12th Class Chemistry Chapter 8 Short Questions Preparation "

Chemistry - 12th Class Chemistry Chapter 8 Short Questions Preparation

Why pie bond is more reactive than alpha bond?

Define Ramy nickel.Give its use.

Describe nitration of methane.

Why are some hydrocarbons called saturated and other unsaturated?

Define Hydrogenation,

Give three use of methane?

Why ethene is more reactive than ethyne towards additions reactions?

Explain acidic nature of ethyne?

What is effect of branching on boiling of alkanes?

How ethene can be prepared by Kolb's electrolysis?

Prepare Complete Set Wise Questions For Chapter 8 "12th Class Chemistry Chapter 8 Short Questions Preparation "

Set 1

Set 2

12th Class Chemistry Chapter 8 Short Questions Preparation - Set 1

Why pie bond is more reactive than alpha bond?

Define Ramy nickel.Give its use.

Describe nitration of methane.

Why are some hydrocarbons called saturated and other unsaturated?

Define Hydrogenation,

Give three use of methane?

Why ethene is more reactive than ethyne towards additions reactions?

Explain acidic nature of ethyne?

What is effect of branching on boiling of alkanes?

How ethene can be prepared by Kolb's electrolysis?

12th Class Chemistry Chapter 8 Short Questions Preparation - Set 2

Why are alkenes also called olefins?

How common name of alkenes are derived?Give common names of CH2=CH2and CH3-CH2=CH2?

The sigma bonds are inert in alkanes.Explain?

Identify the actual product ,when HBr is added to propene.

Why Alkynes are less reactive than alkenes towards Electrophilic Regents?

Why are some hydrocarbons called saturated and other unsaturated?

Write structural formulas for two compound;i) Vinyl acetylene ii) But-3-en-yne

Alkanes are less reactive than alkenes. Comment?

Why pie bond is more reactive than alpha bond?

Explain acidic nature of ethyne?

12th Class Chemistry Chapter 8 Preparation

How common name of alkenes are derived?Give common names of CH₂=CH₂and CH₃-CH₂=CH_2?