Fsc Part 2 Online Preparation for Chemistry Chapter 12 (Aldehydes and Ketones)

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

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Chemistry - 12th Class Chemistry Chapter 12 Short Questions Preparation

Question # 1

Write down mechanism of Cannizzaro reaction?

Ans 1: The hydroxid ion act as a nucleophile. It attacks ion the electrophile carbonyl carbons to form a complex anion.

Question # 2

Justify that Cannizzaro reaction is self oxidation-reduction reaction?

Ans 1: Cannizzaro reaction is a disproportion reaction.two molecules of the aldehyde are involved one molecule being converted into the corresponding alcohol (the reduce product)and the other into the acid in the salt form(the oxidation process).

Question # 3

How aldehyde reacts with hydrdzine?.

Ans 1: Aldehyde react with phenyl hydrazine to form phenylhydrazone in the presence of an acid.

Question # 4

Give formula of formaldehyde and acetaldehyde.

Ans 1: Formula of formaldehyde : HCHO
Formula of acetaldehyde: CH₃CHO

Question # 5

Addition of HCN on aldehydes and ketones is abase catalyzed reaction?

Ans 1: Hydrogen cyanide adds to aldehydes and ketones to form cyanohydrines. The reaction is carried out by adding slowly a mineral acid to an aqueous solution of sodium cyanide,The acid generates HCN from sodium cyanide in SItu.

Question # 6

What is silver mirror test?What is its improvement?

Ans 1: Aldehyde form silver mirror with Tollen's reagent .Add Tollen's reagent to aldehyde solution in a test tube and war,.A silver mirror is formed on the inside of the test tube.

Question # 7

What is halofrom reaction?

Ans 1: Acetaldehyde and methyl ketones react with halogens in the presence of sodium hydroxide to give haloform this reaction is called haloform reaction,The term haloform is used for the distinguish acetaldehyde fromother aldehydes.

Question # 8

Fehling solution reacts with aldehydes to give red ppt,Justify it?

Ans 1: Aliphatic aldehydes form a brick red precipitate with Fehling solution,To an aldehyde solution and Fehling solution and boil .A brick red precipitate of cuprous oxide id formed. Ketones do not give this test,.

Question # 9

Define Aldol condensation.

Ans 1: Aldehydes and ketons possessing a-hydrogen atoms reacts with cold dilute solution of an alkali to form addition products known as aldols,The name aldols is given to the products because it contain both aldehyde and alcohol functional groups,In this process two molecules of the same carbonyl compound condense to form an aldol.

Question # 10

What is Formalin?

Ans 1: Methyl alchohol is oxidized to gaseous formaldehyde which is absorbed in water,The resulting mixture is called formalin.Formalin is a mixture of 40% formaldehyde ,8% methyl alchohol and 52% water.

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

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Set 2

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Set 3

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

Question # 1

Write down mechanism of Cannizzaro reaction?

Ans 1: The hydroxid ion act as a nucleophile. It attacks ion the electrophile carbonyl carbons to form a complex anion.

Question # 2

Justify that Cannizzaro reaction is self oxidation-reduction reaction?

Ans 1: Cannizzaro reaction is a disproportion reaction.two molecules of the aldehyde are involved one molecule being converted into the corresponding alcohol (the reduce product)and the other into the acid in the salt form(the oxidation process).

Question # 3

How aldehyde reacts with hydrdzine?.

Ans 1: Aldehyde react with phenyl hydrazine to form phenylhydrazone in the presence of an acid.

Question # 4

Give formula of formaldehyde and acetaldehyde.

Ans 1: Formula of formaldehyde : HCHO
Formula of acetaldehyde: CH₃CHO

Question # 5

Addition of HCN on aldehydes and ketones is abase catalyzed reaction?

Ans 1: Hydrogen cyanide adds to aldehydes and ketones to form cyanohydrines. The reaction is carried out by adding slowly a mineral acid to an aqueous solution of sodium cyanide,The acid generates HCN from sodium cyanide in SItu.

Question # 6

What is silver mirror test?What is its improvement?

Ans 1: Aldehyde form silver mirror with Tollen's reagent .Add Tollen's reagent to aldehyde solution in a test tube and war,.A silver mirror is formed on the inside of the test tube.

Question # 7

What is halofrom reaction?

Ans 1: Acetaldehyde and methyl ketones react with halogens in the presence of sodium hydroxide to give haloform this reaction is called haloform reaction,The term haloform is used for the distinguish acetaldehyde fromother aldehydes.

Question # 8

Fehling solution reacts with aldehydes to give red ppt,Justify it?

Ans 1: Aliphatic aldehydes form a brick red precipitate with Fehling solution,To an aldehyde solution and Fehling solution and boil .A brick red precipitate of cuprous oxide id formed. Ketones do not give this test,.

Question # 9

Define Aldol condensation.

Ans 1: Aldehydes and ketons possessing a-hydrogen atoms reacts with cold dilute solution of an alkali to form addition products known as aldols,The name aldols is given to the products because it contain both aldehyde and alcohol functional groups,In this process two molecules of the same carbonyl compound condense to form an aldol.

Question # 10

What is Formalin?

Ans 1: Methyl alchohol is oxidized to gaseous formaldehyde which is absorbed in water,The resulting mixture is called formalin.Formalin is a mixture of 40% formaldehyde ,8% methyl alchohol and 52% water.

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

Question # 1

How formaldehyde is prepared on industrial scale?

Ans 1: Formaldehyde is manufactured by passing a mixture of methanol vaporous and air over iron oxide molybdenum oxide or silver catalyst at 500 C.

Question # 2

Explain one method of formation of formaldehyde form methyl alchohol.

Ans 1: Formaldehyde is prepared in laboratory by passing a mixture of methyl alcohol vaporous and air over plantinized asbestos or copper or silver catalyst at 300 C.Acetaldehyde is prepared in laboratory by the oxidation of ethyl alchohol with acidified sodium dichromate solution.

Question # 3

How will you distinguished between ethanal and propanal?

Ans 1: Ethanal forms yellow precipitate of iodoform with an alkaline solution of iodoine,Propanal will not give this test.

Question # 4

Write down mechanism of Cannizzaro reaction?

Ans 1: The hydroxid ion act as a nucleophile. It attacks ion the electrophile carbonyl carbons to form a complex anion.

Question # 5

What is sodium bisulphate test?

Ans 1: Sodium bisulphate test: Aldehydes and small methyl ketons from a crystalline white precipitate with saturated sodium bisulphite solution.

Question # 6

What is iodoform test?

Ans 1: The haloform reaction using iodine and aqueous sodium hydroxide is called the iodoform test. It results in the formation of water insoluble iodoform which is yellow solid,iodoform test is used for distinguish ,ethyl ketones from other ketones.

Question # 7

Justify that Cannizzaro reaction is self oxidation-reduction reaction?

Ans 1: Cannizzaro reaction is a disproportion reaction.two molecules of the aldehyde are involved one molecule being converted into the corresponding alcohol (the reduce product)and the other into the acid in the salt form(the oxidation process).

Question # 8

Define Aldol condensation.

Ans 1: Aldehydes and ketons possessing a-hydrogen atoms reacts with cold dilute solution of an alkali to form addition products known as aldols,The name aldols is given to the products because it contain both aldehyde and alcohol functional groups,In this process two molecules of the same carbonyl compound condense to form an aldol.

Question # 9

Addition of HCN on aldehydes and ketones is abase catalyzed reaction?

Ans 1: Hydrogen cyanide adds to aldehydes and ketones to form cyanohydrines. The reaction is carried out by adding slowly a mineral acid to an aqueous solution of sodium cyanide,The acid generates HCN from sodium cyanide in SItu.

Question # 10

What is Cannizzaro reaction?

Ans 1: Aldehydres that have no a hydrogen atom under cannizaro reaction,cannizzaro reaction is a disproportional (self oxidation and reduction reaction).two molecule of the aldehyde are involved one molecule being converted into the corresponding alcohol and the other into the acid in the salt form (the oxidation product).

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12th Class Chemistry Chapter 12 Short Questions Preparation - Set 3

Question # 1

How does an aldehyde react with
1.Hydroxylamine 2.Hydrazine

Ans 1: 1.Hydroxylamine:Aldehyde reacts with hydroxylamine to form oxims in the presence of an acid.
2.Hydrazine : Aldehyde reacts with hydrazinetoform hydrazone in the presence of acid.

Question # 2

What is Cannizzaro reaction?

Ans 1: Aldehydres that have no a hydrogen atom under cannizaro reaction,cannizzaro reaction is a disproportional (self oxidation and reduction reaction).two molecule of the aldehyde are involved one molecule being converted into the corresponding alcohol and the other into the acid in the salt form (the oxidation product).

Question # 3

Write the name of those weal oxidizing agents which can oxidize aldehyde but not the ketone?

Ans 1: Tollen's reagent ,Fehling solution and Bendict's solution.

Question # 4

How aldehyde reacts with hydrdzine?.

Ans 1: Aldehyde react with phenyl hydrazine to form phenylhydrazone in the presence of an acid.

Question # 5

What is sodium bisulphate test?

Ans 1: Sodium bisulphate test: Aldehydes and small methyl ketons from a crystalline white precipitate with saturated sodium bisulphite solution.

Question # 6

What is Tollen's Test?

Ans 1: Aldehydes form silver mirror with Tollen's reagent (ammonical silver nitrate solution).Add tollen's reagent to an aldehyde solution in a test tube and warm,A silver mirror is formed on the inside of the test tube.

Question # 7

Define nucleophilic addition reaction with an example?

Ans 1: Addition of nucleophillic reagent to the substrate in the presence of some catalyst is called nbucleophilic addition reaction.It is due to the unsymmetrical electronics configuration about the carbonyl group,the nucleophilic reagent can start the initial attack on the carbon.

Question # 8

Give industrial preparation of acetaldehydes?

Ans 1: Acetaldehyde is prepared industrially by air oxidation of ethylene using palladium chloride with a cupric chloride promoter.

Question # 9

Give formula of formaldehyde and acetaldehyde.

Ans 1: Formula of formaldehyde : HCHO
Formula of acetaldehyde: CH₃CHO

Question # 10

Write down some used of acetaldehyde?

Ans 1: It is used to make acetaldehyde ammonia used as rubber -accelerator,.It is used as antiseptic inhalant in nasal infections.It is used in silvering of mirrors.

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12th Class Chemistry Chapter 12 Preparation

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Fsc Part 2 Online Preparation for Chemistry Chapter 12 (Aldehydes and Ketones)

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

Chemistry - 12th Class Chemistry Chapter 12 Short Questions Preparation

Write down mechanism of Cannizzaro reaction?

Justify that Cannizzaro reaction is self oxidation-reduction reaction?

How aldehyde reacts with hydrdzine?.

Give formula of formaldehyde and acetaldehyde.

Addition of HCN on aldehydes and ketones is abase catalyzed reaction?

What is silver mirror test?What is its improvement?

What is halofrom reaction?

Fehling solution reacts with aldehydes to give red ppt,Justify it?

Define Aldol condensation.

What is Formalin?

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

Set 1

Set 2

Set 3

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

Write down mechanism of Cannizzaro reaction?

Justify that Cannizzaro reaction is self oxidation-reduction reaction?

How aldehyde reacts with hydrdzine?.

Give formula of formaldehyde and acetaldehyde.

Addition of HCN on aldehydes and ketones is abase catalyzed reaction?

What is silver mirror test?What is its improvement?

What is halofrom reaction?

Fehling solution reacts with aldehydes to give red ppt,Justify it?

Define Aldol condensation.

What is Formalin?

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

How formaldehyde is prepared on industrial scale?

Explain one method of formation of formaldehyde form methyl alchohol.

How will you distinguished between ethanal and propanal?

Write down mechanism of Cannizzaro reaction?

What is sodium bisulphate test?

What is iodoform test?

Justify that Cannizzaro reaction is self oxidation-reduction reaction?

Define Aldol condensation.

Addition of HCN on aldehydes and ketones is abase catalyzed reaction?

What is Cannizzaro reaction?

12th Class Chemistry Chapter 12 Short Questions Preparation - Set 3

How does an aldehyde react with1.Hydroxylamine 2.Hydrazine

What is Cannizzaro reaction?

Write the name of those weal oxidizing agents which can oxidize aldehyde but not the ketone?

How aldehyde reacts with hydrdzine?.

What is sodium bisulphate test?

What is Tollen's Test?

Define nucleophilic addition reaction with an example?

Give industrial preparation of acetaldehydes?

Give formula of formaldehyde and acetaldehyde.

Write down some used of acetaldehyde?

12th Class Chemistry Chapter 12 Preparation

How does an aldehyde react with
1.Hydroxylamine 2.Hydrazine