To help students access the accurate solutions to all NCERT Exemplar problems of class 12 Chemistry, our experts have solved all the questions in detail but simple language.
Here we are providing the NCERT Exemplar solutions for CBSE Class 12 Chemistry chapter 11, Alcohols, Phenols and Ethers. All these solutions have been prepared by the subject experts and have been revised to bring the accurate study material for our students. These solutions have been collated in the form of PDF which students can download for free of cost and refer the same when required.
Few problems along with their solutions from this chapter are given follows:
Question. 5 The process of converting alkyl halides into alcohols involves ………….. .
(a) Addition reaction (b) Substitution reaction
(c) Dehydrohalogenation reaction (d) Rearrangement reaction
Answer. (b) Substitution reaction
An addition reaction is the one where two or more molecules combine to form a larger one. These reactions occur to change the unsaturated compound to saturated compound. In dehydrohalogenation reaction, alkyl halides give alkenes.
Rearrangement gives the structural isomers of the reactant while in substitution reaction one of the group or an atom is replaced by other group. Therefore, the process of converting alkyl halides into alcohols involves substitution reaction.
Reaction of alkyl halides
Primary alkyl halides – SN 2
Secondary alkyl halides- SN 1
Tertiary alkyl halides - SN 1
Q. Phenol is less acidic than…
(a) ethanol (b) o-nitrophenol
(c) o-methylphenol (d) o-methoxyphenol
Ans. (b) o-nitrophenol
In o-nitrophenol, nitro group is present at ortho position. Presence of electron withdrawing group at ortho position increases the acidic strength. On the other hand, in o-methylphenol and in o-methoxyphenol, electron releasing group (–CH3, –OCH3) are present.
Presence of these groups at ortho or para positions of phenol decreases the acidic strength of phenols. So, phenol is less acidic than o - nitrophenol.
Q. Explain why p-nitrophenol is more acidic than phenol?
Ans. Nitro group of phenol produces - I and - R effect. Because of these two effects –NO2 group is electron withdrawing in nature. So, the electron density in the O–H bond of p-nitrophenol decreases relative to the O–H bond of phenol.
Decrease in electron density of the O–H bond of p-nitrophenol, the polarity of O–H bond is decrease and in turn make it more acidic than phenol.
Q. Assertion (A) p-nitrophenol is more acidic than phenol.
Reason (R) Nitro group helps in the stabilisation of the phenoxide ion by dispersal of negative charge due to resonance.
Ans. (a) Assertion and reason both are correct and reason is correct explanation of assertion, p-nitrophenol is more acidic than phenol because nitro group helps in the stabilisation of the phenoxide ion by dispersal of negative charge due to resonance.
Find below the links to download Class 12 Chemistry NCERT Exemplar Solutions for chapter 11- Alcohols, Phenols and Ethers:
Link to Download Solutions
Multiple Choice Questions (Type-I)
Multiple Choice Questions (Type-II)
Short Answer Type Questions
Matching Columns Type Questions
Assertion and Reason Type Questions
Long answer types questions
Class 12 Chemistry NCERT Exemplar Problems: Alcohols, Phenols and Ethers
The NCERT Exemplar problems are considered to be the most applicative kind of problems which help to enhance a student’s critical thinking and problem solving ability. These problems form the best practice source to prepare effectively for board exams and the medical entrance tests. So, it’s very important for students to practice the NCERT exemplar problems to prepare well for the boards and the competitive exams.
Important topics discussed in Class 12 Chemistry chapter – Alcohols, Phenols and Ethers, are:
- Structures of Functional Groups
- Alcohols and Phenols
- Some Commercially Important Alcohols
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