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

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 # 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

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.

Question # 4

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 # 5

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 # 6

What is heat of combustion?

Ans 1: Burning of alkane in presence of oxygen is known as combustion,Complete combustion of an alkene yield CO₂,H₂O and heat.The amount to heat evolved when one mole of a hydrocarbon is brunt to CO₂and H₂O is called heat of combustion.

Question # 7

What is Hydrogenolysis?Give an example.

Ans 1: Hydrogenolysis is a chemical reaction whereby a carbon -carbon or carbon-heteroatom single bond is cleaved or undergoes lysis by hydrogen.The heteroatom may vary,but it usually is oxygen,nitrogen or sulfur.A related reaction is hydrogenation,where hydrogen is added to the molecule,without cleaving bonds.
R-X + H-H-----> R-H + HX

Question # 8

Describe a test for the presence of unsaturation in organic molecules.

Ans 1: When alkenes are treated with mild oxidizing reagents like dilute alkaline KMnO₄solution (Bayer's Reagent) at low temperature,hydroxylation of double bond occur resulting in the formation of dihydroxy compounds known as vicinal glycols. The pink colouration of KMnO₄solution is discharged.
3CH₂=CH₂+ 2KMnO₄+ 4H₂O---->HO-CH₂-CH₂-OH+2MnO₂+2KOH

Question # 9

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 # 10

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.

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

Set 1

10 Questions
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Set 2

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

Question # 1

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 # 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

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.

Question # 4

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 # 5

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 # 6

What is heat of combustion?

Ans 1: Burning of alkane in presence of oxygen is known as combustion,Complete combustion of an alkene yield CO₂,H₂O and heat.The amount to heat evolved when one mole of a hydrocarbon is brunt to CO₂and H₂O is called heat of combustion.

Question # 7

What is Hydrogenolysis?Give an example.

Ans 1: Hydrogenolysis is a chemical reaction whereby a carbon -carbon or carbon-heteroatom single bond is cleaved or undergoes lysis by hydrogen.The heteroatom may vary,but it usually is oxygen,nitrogen or sulfur.A related reaction is hydrogenation,where hydrogen is added to the molecule,without cleaving bonds.
R-X + H-H-----> R-H + HX

Question # 8

Describe a test for the presence of unsaturation in organic molecules.

Ans 1: When alkenes are treated with mild oxidizing reagents like dilute alkaline KMnO₄solution (Bayer's Reagent) at low temperature,hydroxylation of double bond occur resulting in the formation of dihydroxy compounds known as vicinal glycols. The pink colouration of KMnO₄solution is discharged.
3CH₂=CH₂+ 2KMnO₄+ 4H₂O---->HO-CH₂-CH₂-OH+2MnO₂+2KOH

Question # 9

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 # 10

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.

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

Question # 1

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 # 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

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 # 4

What is Hydrogenolysis?Give an example.

Ans 1: Hydrogenolysis is a chemical reaction whereby a carbon -carbon or carbon-heteroatom single bond is cleaved or undergoes lysis by hydrogen.The heteroatom may vary,but it usually is oxygen,nitrogen or sulfur.A related reaction is hydrogenation,where hydrogen is added to the molecule,without cleaving bonds.
R-X + H-H-----> R-H + HX

Question # 5

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.

Question # 6

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 # 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

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 # 9

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 # 10

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.

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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

Define Ramy nickel.Give its use.

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

How ethene can be prepared by Kolb's electrolysis?

Alkanes are less reactive than alkenes. Comment?

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

What is heat of combustion?

What is Hydrogenolysis?Give an example.

Describe a test for the presence of unsaturation in organic molecules.

Define Hydrogenation,

Why pie bond is more reactive than alpha bond?

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

Define Ramy nickel.Give its use.

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

How ethene can be prepared by Kolb's electrolysis?

Alkanes are less reactive than alkenes. Comment?

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

What is heat of combustion?

What is Hydrogenolysis?Give an example.

Describe a test for the presence of unsaturation in organic molecules.

Define Hydrogenation,

Why pie bond is more reactive than alpha bond?

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

Describe nitration of methane.

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

Define Hydrogenation,

What is Hydrogenolysis?Give an example.

How ethene can be prepared by Kolb's electrolysis?

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

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

The sigma bonds are inert in alkanes.Explain?

Why are some hydrocarbons called saturated and other unsaturated?

What is effect of branching on boiling of alkanes?

12th Class Chemistry Chapter 8 Preparation

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

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

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