Recently Viewed Questions of Class 12th chemistry. In this case, the nucleophile CN– can easily attack without any steric hindrance. Di-tert-butyl ketone < Methyl tert-butyl ketone < Acetone < Acetaldehyde (vii) p,p‘-Dihydroxybenzophenone (viii) Hex-2-en-4-ynoic acid (ii) Since Tollens Reagent has a relatively short shelf life, the reagent is not commercially sold. (ii) Now, any group that will help stabilise the negative charge will increase the stability of the carboxyl ion and as a result, will increase the strength of the acid. (a) Tollen’s test (ix) Benzoic acid to m- Nitrobenzyl alcohol Acetyl chloride and acetic anhydride are commonly used as acetylating agents. (vii) Ethanal and Propanal (i) Cyanohydrin (ii) Acetal Q19 :An organic compound contains 69.77% carbon, 11.63% hydrogen and rest oxygen. (i) (iii) During the preparation of esters from a carboxylic acid and an alcohol in the presence of an acid catalyst, the water or the ester should be removed as soon as it is formed. (iii) Identify the compound. Aldehydes are oxidised to the corresponding acid and silver in Tollens reagent is reduced from +1 oxidation state to its elemental form. of iodoform. Why? < 3,4-Dinitrobenzoic acid. An organic compound with the molecular formula C9H10O forms 2,4-DNP derivative, reduces Tollens’ reagent and undergoes Cannizzaro reaction. However, only one is involved in the formation of semicarbazones. (iv) 4-Oxopentanal Aldehydes reacts with Tollens reagent gives a grey-black precipitate or a silver mirror. (i) (C) on dehydration gives but-1-ene. Thus, the ratio of the number of carbon, hydrogen, and oxygen atoms in the organic compound can be given as: (i)

(Gluconic acid)

[Use and at 298K]
Now answer the following three questions:
Q. Ammonia is always is added inn this reaction. This process involves the substitution of an acetyl group for an active hydrogen atom. Therefore, the given compound must be an aldehyde. To identify and characterize aldehydes and ketones, 2, 4 – DNP derivatives are used. (iii) Ethanol to 3-Hydroxybutanal Question 4. Answer : Prinses Margrietplantsoen 33 2595 AM 's-Gravenhage When aldol condensation is carried out between two different aldehydes, or two different ketones, or an aldehyde and a ketone, then the reaction is called a cross-aldol condensation. 5 × 12 + 10 ×1 + 1 × 16 Give simple chemical tests to distinguish between the following pairs of compounds. Phenol reacts with neutral FeCl3 to form an iron-phenol complex giving violet colouration. Give an example of the reaction in each case. (iii) Cannizzaro reaction All the solutions given in this page are solved based on CBSE Syllabus and NCERT guidelines. Ketones will not give silver mirror test. On vigorous oxidation, it gives 1, 2-benzenedicarboxylic acid. Hence, these compounds do not undergo either aldol condensation or cannizzaro reactions. p – Nitrobenzaldehyde, Acetophenone. (iv) Decarboxylation also takes place when aqueous solutions of alkali metal salts of carboxylic acids are electrolyzed. Therefore, the empirical formula of the compound is C5H10O. Further, in resonating structures I’ and II’, the negative charge is delocalized over two oxygen atoms. Answer : Compound (iv) Benzophenone is a ketone having no α-hydrogen atom and compound (viii) Butan-1-ol is an alcohol. Sodium hydroxide present in the solution maintains a basic pH i.e. It is given that the compound (with molecular formula C9H10O) forms 2, 4-DNP derivative and reduces Tollen’s reagent. Sodium hydroxide present in the solution maintains a basic pH i.e. The compounds (i) Methanal, (iii) Benzaldehyde, and (ix) 2, 2-dimethylbutanal do not have any α-hydrogen. (ii) (i) The 2,4-dinitrophenylhydrazone of benzaldehyde Solution: Question 6. Answer : Aldehydes respond to Fehling’s test, but ketones do not. Thus, the arrangement of the given compounds in the increasing order of their boiling points is given by: (b) Iodoform test Live Classes, Video Lectures, Test Series, Lecturewise notes, topicwise DPP, dynamic Exercise and much more on Physicswallah App. On vigorous oxidation, it gives 1, 2-benzenedicarboxylic acid. Silver Mirror is formed. Also working on Class 12 Chemistry Chapter 12 Aldehydes Ketones and Carboxylic Acids NCERT Solutions will be most helpful to the students to solve their Homeworks and Assignments on time. On vigorous oxidation, it gives 1, 2-benzenedicarboxylic acid. (iii) If R’ is H, then it is known as aldoxime and if R’ is an organic side chain, it is known as ketoxime. (iv), Q6 : Give the IUPAC names of the following compounds: Q17 :Complete each synthesis by giving missing starting material, reagent or products (v) 4-Chloropentan-2-one (vi) 3-Bromo-4-phenylpentanoic acid Students can also download NCERT Solutions for Class 12 Chemistry Chapter 12 Aldehydes Ketones and Carboxylic Acids PDF to access them even in offline mode. (iii) 2-Methylcyclopentanecarboxylic acid Answer : Solution: Identify the compound. (iii) Semicarbazide and weak acid Answer : Students who are preparing for their Class 12 exams must go through NCERT Solutions for Class 12 Chemistry Chapter 12 Aldehydes Ketones and Carboxylic Acids. Tollens’ test, also known as silver-mirror test, is a qualitative laboratory test used to distinguish between an aldehyde and a ketone.. (i) Acetylation Answer : On the other hand, the -I effect of F decreases the electron density on the O-H bond. (v) p-Nitrobenzaldehyde. (v) Di-sec-butyl ketone (i)Ethanal, Propanal, Propanone, Butanone. 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