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In NCERT exemplar Class 12 Chemistry solutions chapter 12, students will learn about the physical properties, uses and chemical reactions of very crucial hydrocarbons like Aldehydes, Ketones, and Carboxylic Acids alongside it’s nomenclatures and various structures of the carboxyl groups easily in details etc. NCERT exemplar Class 12 Chemistry solutions chapter 12 pdf download is to be available for students. Using it they can understand the concepts better in offline mode too.
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Question:1
Answer:
The answer is the option (ii) On addition of water to but-1-yne in the presence of and , 2-butanone is obtained (by Markovnikoff’s rule).
Question:2
Which of the following compounds is most reactive towards nucleophilic addition reactions?
Answer:
The answer is the option (i) (an aldehyde) is generally considered more reactive than ketones towards nucleophilic addition reactions. Ketones have 2 large substituents compared to 1 in aldehydes, that hinder the nucleophilic approach. Aldehydes are also considered more reactive because the 2 alkyl groups lead to the reduction of electrophilicity of the carbonyl carbon of ketone by releasing electron in its direction.
The reactivity order can be given as:
Question:3
The correct order of increasing acidic strength is _____________.
(i) Phenol < Ethanol < Chloroacetic acid < Acetic acid
(ii) Ethanol < Phenol < Chloroacetic acid < Acetic acid
(iii) Ethanol < Phenol < Acetic acid < Chloroacetic acid
(iv) Chloroacetic acid < Acetic acid < Phenol < Ethanol
Answer:
The answer is the option (iii) Due to formation of more stable conjugate base after removal of phenol is more stable than the alcohol.
On the other hand, the stable conjugate base formed after removing makes carboxylic acid more acidic than phenol.
In case chloroacetic acid, the presence of electron withdrawing chlorine group makes it more acidic compared to the acetic acid.
Question:4
Compound can be prepared by the reaction of _____________.
(i) Phenol and benzoic acid in the presence of
(ii) Phenol and benzoyl chloride in the presence of pyridine
(iii) Phenol and benzoyl chloride in the presence of
(iv) Phenol and benzaldehyde in the presence of palladium
Answer:
The answer is the option (ii) The compound can be prepared by the given below reaction. In this, the phenol is made to react with acid chloride in presence of an alkali. The alkali used is pyridine and acid chloride is benzoyl chloride.
Question:5
The reagent which does not react with both, acetone and benzaldehyde.
(i) Sodium hydrogen sulphite
(ii) Phenyl hydrazine
(iii) Fehling’s solution
(iv) Grignard reagent
Answer:
The answer is the option (iii) Fehling’s solution is the reagent that does not react with both acetone and benzaldehyde.
Question:6
Cannizaro’s reaction is not given by _____________.
Answer:
The answer is the option (iv)
contains 3 -hydrogens while other three compounds have no any -hydrogen. Hence, Cannizzaro’s reaction is given by them. Aldehydes without any alpha hydrogen undergo reduction and self-oxidation reaction when treated with conc. Alkali.
Question:7
Which product is formed when the compound is treated with concentrated aqueous solution?
Answer:
(ii) Benzaldehyde does not have any hydrogen. When reacted with aqueous solution, it gives Cannizzaro’s reaction.
Question:8
Structure of ‘A’ and type of isomerism in the above reaction are respectively.
(i)
(ii)
(iii)
(iv)
Answer:
The answer is the option (iv) A undergoes tautomerism to form acetone.
Question:9
Compounds A and C in the following reaction are __________.
(i) identical
(ii) positional isomers
(iii) functional isomers
(iv) optical isomers
Answer:
Thus, and are positional isomers.
We know that acetaldehyde when treated with Grignard reagent followed by hydrolysis gives propane 2-ol.
Question:10
Which is the most suitable reagent for the following conversion?
(i) Tollen’s reagent
(ii) Benzoyl peroxide
(iii) and solution
(iv) and solution
Answer:
The answer is the option (iii) Iodoform test is most suitable for the given reaction.
Question:11
Which of the following compounds will give butanone on oxidation with alkaline solution?
(i)
(ii)
(iii) Both of these
(iv) None of these
Answer:
The answer is the option (ii). Aldehydes, when treated with common oxidising agents get readily oxidized to carboxylic acids.
Question:12
In Clemmensen Reduction carbonyl compound is treated with _____________.
(i)
(ii)
(iii)
(iv)
Answer:
The answer is the option (i) Clemmensen reduction is used in the conversion of carbonyl group to group. In this reaction, zinc amalgam and act as reagent.
Question:13
Which of the following compounds do not undergo aldol condensation ?
Answer:
The answer is the option (ii, iv)
Aldol condensation takes place only if hydrogen is present. In the reaction, aldehydes and ketones with 1 or more than 1 alpha hydrogen react in presence of dilute alkali to form aldol and ketol respectively.
Question:14
Treatment of compound with solution yields
(i) Phenol
(ii) Sodium phenoxide
(iii) Sodium benzoate
(iv) Benzophenone
Answer:
The answer is the option (ii, iii) We get sodium phenoxide and sodium benzoate by nucleophilic substitution reaction.
Question:15
Which of the following conversions can be carried out by Clemmensen Reduction?
(i) Benzaldehyde into benzyl alcohol
(ii) Cyclohexanone into cyclohexane
(iii) Benzoyl chloride into benzaldehyde
(iv) Benzophenone into diphenyl methane
Answer:
The answer is the option (ii, iv)
Clemmensen reduction is used in the conversion of carbonyl group of aldehydes and ketones to group when treated with zinc amalgam and conc. . It is used to convert cyclohexanone into cyclohexane and benzophenone into diphenyl methane.
Question:16
Through which of the following reactions number of carbon atoms can be increased in the chain?
(i) Grignard reaction
(ii) Cannizaro’s reaction
(iii) Aldol condensation
(iv) HVZ reaction
Answer:
The answer is the option (i,iii) Grignard reaction is used to increase the number of carbon atom in chain. Aldol condensation increases the number of carbon atom in the chain for aldehydes and ketones.
Question:17
Benzophenone can be obtained by ____________.
(i)
(ii)
(iii)
(iv)
Answer:
The answer is the option (i,ii) Benzophenone can be obtained by either of benzoyl chloride + diphenylcadmium or benzoyl chloride+ benzene+ . The latter is referred to as Friedel-Craft acylation reaction.
Question:18
The answer is the option (i,ii) The 2 possible orientation of a planar molecule of carbonyl compound in case of nucleophilic attack are:
The nucleophililic attack can occur either from front or rear side.
Question:19
Why is there a large difference in the boiling points of ?
Answer:
There is a huge difference in the boiling points of due to the presence of intermolecular hydrogen bonding between groups in alcohol.
Question:20
Write a test to differentiate between and .
Answer:
The answer is Idoform test. There is a group in and that is why it will give a positive iodoform test.
Question:24
Reactions for obtaining benzalchloride and benzaldehyde from it are:
Question:25
The electrophile produced in the reaction of benzene with benzoyl chloride in the presence of anhydrous AlCl3 is benzoylium cation. The product formed in this reaction is benzophenone. This reaction is called Friedel Craft's acylation reaction.
Question:26
The products formed on oxidation of 2, 5-dimethylhexan-3-one are: -
2-Methylpropanoic acid
Ethanoic acid and
Methanoic acid.
3-Methylbutanoic acid
Question:27
The electron-withdrawing group increase the acidity of carboxylic acids since they stabilize the conjugate base by delocalization of charge. Whereas the electron donating group decrease the acidity as the resulting conjugate base is unstable.
Higher the electronegativity, greater the acidic strength.
Question:28
On reaction of propanal with 2-methyl propanal in the presence of , aldehyde mixture is formed.
Question:29
It is given that B and A on heating together in the presence of acid produces a fruity smelling compound which is ester.
Carboxylic Acid
Alcohol
Ester Group
Question:30
and groups are electron withdrawing groups that increase the acidity due to stable nature of resulting conjugate base. Whereas the electron-donating group decrease the acidity as the resulting conjugate base is unstable.
Higher the electronegativity, greater the acidic strength.
Question:31
In carbonyl groups, carbon acquires a partial positive charge because oxygen is more electronegative. Thus, carbonyl group is polar in nature and hence susceptible to nucleophilic addition reaction. Alkenes, on the other hand are non-polar and electron abundant; making them susceptible to electrophilic addition reaction.
Question:32
Carboxylic acid doesnt show nucleophilic substitution reaction as because of presence of lone pair atoms on O atom of OH group decreases electrophilic character of carbonyl carbon by resonance.. Hence partial positive charge decreases and therefore it doesnt show nucleophilic substitution reactions
Question:33
Identify the compounds A, B and C in the following reaction.
Answer:
Compound A is
Compound B is
Compound C is
Question:34
Acidity depends upon the stability of the resulting conjugate base. In case of carboxylic acid, equivalent resonance structures stabilize the carboxylate ion as the negative charge is at the more electronegative oxygen atom. Phenoxide ion, conjugate base of phenol does not have equivalent resonance structure as the negative charge is on the less electronegative carbon atom.
Question:35
Question:36
Answer:
The reason is formation of polysubstituted products. Friedel-craft’s acylation reaction can be used to avoid the formation of these products.
Question:37
Can Gatterman-Koch reaction be considered similar to Friedel Craft’s acylation? Discuss.
Answer:
Yes, the Gattermann-Koch reaction can be considered similar to Friedel Craft’s acylation reaction. In Gattermann-Koch reaction introduction of group to the benzene nucleus takes place by reacting with gas. In Friedel-Crafts acylation reactions, treatment of benzene or any arene with an acid chloride in presence of anhydrous takes place. In this RCO group is introduced.
Question:38
Match the common names given in Column I with the IUPAC names given in Column II
Column I (Common names) | Column II (IUPAC names) |
(i) Cinnamaldehyde | (a) Pentanal |
(ii) Acetophenone | (b) Prop-2-enal |
(iii) Valeraldehyde | (c) 4-Methylpent -3-en-2-one |
(iv) Acrolein | (d) 3-phenylprop-2-enal |
(v) Mesityl oxide | (e) 1-Phenylethanone |
Answer:
(i d), (ii e), (iii a), (iv b), (v c)
Question:39
Match the acids given in Column I with their correct IUPAC names given in Column II.
Column I (Acids) | Column II(IUPAC names) |
(i) Phthalic acid | (a) Hexane-1,6-dioic acid |
(ii) Oxalic acid | (b) Benzene-1, 2-dicarboxylic acid |
(iii) Succinic acid | (c) Pentane -1 , 5-dioic acid |
(iv) Adipic acid | (d) Butane -1, 4-dioic acid |
(v) Glutaric acid | (e) Ethane-1,2-dioic acid |
Answer:
(i b), (ii e), (iii d), (iv a), (v c)
Question:40
Match the reactions given in Column I with the suitable reagents given in Column II.
Column I (Reactions) | Column II (Reagents) |
(i) Benzophenone Diphenylmethane | (a) |
(ii) Benzaldehyde 1-Phenylethanol | (b) |
(iii) Cyclohexanone Cyclohexanol | (c) |
(iv) Phenyl benzoate Benzaldehyde | (d) |
Answer:
(i c), (ii d), (iii a), (iv b)
Question:41
Match the example given in Column I with the name of the reaction in Column II
Column I (Examples) | Column II (Reaction) | ||
(i) | (a) | Friedel-Crafts acylation | |
(ii) | (b) | HVZ reaction | |
(iii) | (c) | Aldol condensation | |
(iv) | (d) | Cannizzaro's reaction | |
(v) | (e) | Rosenmund's reduction | |
(vi) | (f) | Stephen's reaction |
Answer:
(i e), (ii d), (iii a), (iv b), (v f), (vi c)
Question:42
In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Formaldehyde is a planar molecule.
Reason: It contains hybridised carbon atom.
(i) Assertion and reason both are correct and the reason is the correct explanation of assertion.
(ii) Assertion and reason both are wrong statements.
(iii) The assertion is a correct statement but the reason is the wrong statement.
(iv) The assertion is a wrong statement but the reason is the correct statement.
(v) Assertion and reason both are correct statements but the reason is not the correct
explanation of assertion.
Answer:
The answer is the option (i). Formaldehyde contains hybridized carbon atom. That is why it is a planar molecule. Both the assertion and reason are correct, and reason is correct explanation of assertion.
Question:43
In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Compounds containing group are easily oxidised to corresponding carboxylic acids.
Reason: Carboxylic acids can be reduced to alcohols by treatment with
(i) Assertion and reason both are correct and the reason is the correct explanation of assertion.
(ii) Assertion and reason both are wrong statements.
(iii) The assertion is a correct statement but the reason is the wrong statement.
(iv) The assertion is a wrong statement but the reason is the correct statement.
(v) Assertion and reason both are correct statements but the reason is not the correct
explanation of assertion
Answer:
The answer is the option (v). Due to high electronegativity of oxygen, carbonyl group in aldehydes are a strong electron-withdrawing group. This weakens the bond in aldehydes. Even a weak oxidizing agent can oxidize the aldehydes into the corresponding carboxylic acids.
Question:44
In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: The -hydrogen atom in carbonyl compounds is less acidic.
Reason: The anion formed after the loss of the -hydrogen atom is resonance stabilised.
(i) Assertion and reason both are correct and the reason is the correct explanation of assertion.
(ii) Assertion and reason both are wrong statements.
(iii) The assertion is a correct statement but the reason is the wrong statement.
(iv) The assertion is a wrong statement but the reason is the correct statement.
(v) Assertion and reason both are correct statements but the reason is not the correct
explanation of assertion
Answer:
The answer is the option (iv). The -hydrogen atom in carbonyl compounds is more acidic. Carboxylic acids on dissociation in water give resonance stabilized carboxylate anions and hydronium ion.
Question:45
In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Aromatic aldehydes and formaldehyde undergo Cannizaro reaction.
Reason: Aromatic aldehydes are almost as reactive as formaldehyde.
(i) Assertion and reason both are correct and the reason is the correct explanation of assertion.
(ii) Assertion and reason both are wrong statements.
(iii) The assertion is a correct statement but the reason is the wrong statement.
(iv) The assertion is a wrong statement but the reason is the correct statement.
(v) Assertion and reason both are correct statements but the reason is not the correct
explanation of assertion.
Answer:
The answer is the option (iii). Aromatic aldehydes and formaldehyde do not have a-hydrogen and thus undergo Cannizzaro’s reaction. Aldehydes with no alpha hydrogen atom undergo oxidation and reduction reaction when treated with conc. Alkali.
Question:46
In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion: Aldehydes and ketones, both react with Tollen’s reagent to form a silver mirror.
Reason: Both, aldehydes and ketones contain a carbonyl group.
(i) Assertion and reason both are correct and the reason is the correct explanation of assertion.
(ii) Assertion and reason both are wrong statements.
(iii) The assertion is a correct statement but the reason is the wrong statement.
(iv) The assertion is a wrong statement but the reason is the correct statement.
(v) Assertion and reason both are correct statements but the reason is not the correct
explanation of assertion.
Answer:
The answer is the option (iv) Aldehyde and ketones both have carbonyl group but only the former undergoes reaction with Tollen’s reagent to give silver mirror.
Question:47
As compound B turns up with a positive result for Fehling’s test, it is an aldehyde. It also gives a positive result to the iodoform test, which implies that it has a group. Compound C with a positive iodoform test and negative Fehling’s test, is a ketone.
Question:48
Answer:
Molecular formula of the compound in question is It is given that ‘A’ does not give Tollens’ or Fehling’s test, making it a ketone. Since we get positive test with 2, 4-DNP and iodoform test, It means it is methyl ketone.
Question:49
will have following isomer.
Compound 1 (Propanal) is more susceptible to a reaction with as carbon atom in carbonyl group acquires more positive charge than carbon atom in compound 2 (propan-2-one). Moreover, there is much less static hindrance in compound 1 compared to compound 2.
Equilibrium is established in this reaction as it is reversible in nature. Addition of an acid hinders the formation of ion and thus, can stop the reaction.
Question:50
Since liquid A forms a bright silver mirror when treated with ammoniacal solution it is an aldehyde.
In the same way, liquid ‘B’ must be a methyl ketone for it does not give test with ammoniacal solution.
Chemical equations for these reactions are :
Also, check NCERT solutions for class 12, other subjects.
Studying the chapter “Aldehydes, Ketones and Carboxylic Acids” from Class 12 Chemistry NCERT exemplar solutions chapter 12 will not only help you to write IUPAC names of different ketones, aldehydes, and carboxylic acids, but will also help you to remember these for future.
- The physical properties and chemical reactions of very important hydrocarbons (from exams point of view) is talked about in detail
- Students will also learn about nomenclatures and various structures of different carboxyl groups with their detailed diagrams provided by Class 12 Chemistry NCERT exemplar solutions chapter 12, which again is very crucial from exam point of view.
- Studying from NCERT exemplar Class 12 Chemistry solutions chapter 12 will help students to understand the concept better
Chapter 1 | |
Chapter 2 | |
Chapter 3 | |
Chapter 4 | |
Chapter 5 | |
Chapter 6 | |
Chapter 7 | |
Chapter 8 | |
Chapter 9 | |
Chapter 10 | |
Chapter 11 | |
Chapter 12 | Aldehydes, Ketones and Carboxylic Acids |
Chapter 13 | |
Chapter 14 | |
Chapter 15 | |
Chapter 16 |
Must read NCERT Solution subject wise
Read more NCERT Notes subject wise
Also Check NCERT Books and NCERT Syllabus here:
Students will learn about physical properties, uses and chemical reactions of very crucial hydrocarbons like Aldehydes, Ketones, and Carboxylic Acids alongside it’s nomenclatures and various structures of the carboxyl groups and the IUPAC names of different ketones, aldehydes, and carboxylic acids.
Our Chemistry teachers prepared these NCERT Class 12 exemplar solutions for chapter 12.
Admit Card Date:04 October,2024 - 29 November,2024
Admit Card Date:04 October,2024 - 29 November,2024
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Application Correction Date:08 October,2024 - 27 November,2024
Hello there! Thanks for reaching out to us at Careers360.
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Qualifications:
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hello mahima,
If you have uploaded screenshot of your 12th board result taken from CBSE official website,there won,t be a problem with that.If the screenshot that you have uploaded is clear and legible. It should display your name, roll number, marks obtained, and any other relevant details in a readable forma.ALSO, the screenshot clearly show it is from the official CBSE results portal.
hope this helps.
Hello Akash,
If you are looking for important questions of class 12th then I would like to suggest you to go with previous year questions of that particular board. You can go with last 5-10 years of PYQs so and after going through all the questions you will have a clear idea about the type and level of questions that are being asked and it will help you to boost your class 12th board preparation.
You can get the Previous Year Questions (PYQs) on the official website of the respective board.
I hope this answer helps you. If you have more queries then feel free to share your questions with us we will be happy to assist you.
Thank you and wishing you all the best for your bright future.
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