Assertion Reason Chemistry Chapter 7 Alcohols, Phenols and Ethers
Questions of Assertion Reason of Chemistry Chapter 7 Alcohols, Phenols and Ethers CBSE Class 12 are very simple to understand as this chapter deals with Alcohols, Phenols and Ethers. To solve assertion reason type questions of Chemistry, a deeper understanding of concept about Classification, Nomenclature, Structures of Functional Groups, Alcohols and Phenols, Some Commercially Important Alcohols and Ethers is required. In order to help the student in solving Assertion Reason type of questions, detailed process is explained.
How to solve Assertion Reason Type Questions?
In Assertion-Reason type of question, two statements are given, first is Assertion and second is called Reason. Student must have to think critically about both the statements in Assertion Reason Questions, since it combines multiple choice questions and true/false type of questions which requires a higher level of understanding.
How many types are there of Assertion Reason Type Questions?
Assertion-Reason type of questions can be asked either with four MCQ options or with five MCQ options. First four options are same in both the cases only one more options is being provided i.e. last one. One extra option increases the difficulty level of the questions.
In assertion reason type of questions, all 4 or 5 options are same for each question, which are as:
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
(e) Both Assertion and Reason are false.
Then a question haunts in every student’s mind, which option is correct and when?
This can be understood clearly with the following table:
| Assertion (A) | Reason (R) | MCQ Options (Fixed for all questions) |
|---|---|---|
| If True | True | (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A). |
| If True | True | (b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A). |
| If True | False | (c) Assertion (A) is true but reason (R) is false. |
| If False | True | (d) Assertion (A) is false but reason (R) is true. |
| If False | False | (e) Both Assertion and Reason are false. |
Now, lets practice some Assertion Reason Questions of Chemistry: Chapter 7 Alcohols, Phenols and Ethers
Read instructions carefully before answering the questions.
For question given below, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true and R is correct explanation of the assertion.
(b) Both A and R are true but R is not the correct explanation of the assertion.
(c) A is true but R is false.
(d) A is false but R is true.
Question.1.
Assertion: The bond angle in alcohols is slightly less than the tetrahedral angle.
Reason: In alcohols, the oxygen of -OH group is attached to sp3 hybridized carbon atom.
Ans.1. (a)
Both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
Question.2.
Assertion: In Lucas test, 3° alcohols react immediately.
Reason: An equimolar mixture of anhyd. ZnCl_{2} and conc. HCl is called Lucas reagent.
Ans.2. (b)
Both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
Question.3.
Assertion: Phenol is more reactive than benzene towards electrophilic substitution reaction.
Reason: In the case of phenol, the intermediate carbocation is more resonance stabilized.
Ans.3. (a)
Both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
Question.4.
Assertion: In case of phenol, bromination takes place even in absence of Lewis acid whereas bromination of benzene takes place in presence of Lewis acid like FeBr_{3} .
Reason: -OH group attached to benzene ring is highly deactivating.
Ans.4. (c)
Assertion is correct but Reason is incorrect.
Question.5.
Assertion: ter – Butyl methyl ether is not prepared by the reaction of ter-butyl bromide with sodium methoxide.
Reason: Sodium methoxide is a strong nucleophile.
Ans.5. (b)
Both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
Question.6.
Assertion: Ethers behave as bases in the presence of mineral acids.
Reason: Due to the presence of lone pairs of electrons on oxygen.
Ans.6. (d)
Assertion and Reason are incorrect.
Question.7.
Assertion: With HI , anisole gives iodobenzene and methyl alcohol.
Reason: Iodide ion combines with smaller group to avoid steric hindrance.
Ans.7. (d)
Assertion and Reason are incorrect.
Question.8.
Assertion: With HI at 373 K, ter-butyl methyl ether gives ter-butyl iodide and methanol.
Reason: The reaction occurs by SN^{2} mechanism.
Ans.8. (c)
Assertion is correct but Reason is incorrect.
Question.9.
Assertion: Ethyl phenyl ether on reaction with HBr form phenol and ethyl bromide.
Reason: Cleavage of C–O bond takes place on ethyloxygen bond due to the more stable phenyl-oxygen bond.
Ans.9. (c)
Assertion is correct but Reason is incorrect.