Chemistry NCERT Exemplar Solutions Class 12th Chapter Eleven
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4 months agoContributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
I. CrO3 in anhydrous medium.
II. Pyridinium chlorochromate.
III. Heat in the presence of Cu at 573K.
KMnO4 is a strong oxidising agent and oxidises the primary alcohol to ketone. Hence cannot be used as a reagent to oxidise primary alcohols to aldehydes.
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4 months agoContributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
Phenol is prepared by:
Dow's process: The chlorobenzene on heating with NaOH, form sodium phenoxide which on hydrolysis with water of acid from phenol.
Diazotization of aniline: Aniline on reacting with nitrous acid at 0-5o C followed by hydrolysis with water form phenol.
Benzene undergoes sulphonation on reacting with oleum to form benzene sulphonic acid which on heating with sodium hydroxide forms sodium phenoxide and then phenol on hydrolysis.
The nucleophilic substitution of haloarenes such as chlorobenzene requires drastic conditions for conversion to phenol so chlorobenz
New answer posted
4 months agoContributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
I. H2/Pd
II. LiA1H4
III. NaBH4
Aldehydes and ketones are converted to alcohols by catalytic hydrogenation.The reagents used to convert the aldehydes to alcohol are by H2/Pd, lithium aluminium hydride (LiA1H4), and sodium borohydride (NaBH4).
New answer posted
4 months agoContributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
(I) Propan- 1-ol. butan-2-ol. butan- 1-ol. pentan- 1-ol
The compounds Propan-l-ol, butan-2-ol, butan-1-ol, pentan-1-ol belong to the alcohol family. The structure of the given alcohols are as shown below:
With increase in the molecular weight, the boiling points of alcohols increase. Hence, butan-1-ol has higher boiling point than propan-1-ol. Similarly, pentan-1-ol has higher boiling point than butan-1-ol.
Hence, the increasing order of the boiling points of alcohols is propan-1-ol < butan-1-ol < pentan-1-ol.
With increase in the branching of alkyl groups, the boiling point of alcohols dec
Contributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
(III) b < c < a
The reaction will proceed by SN1 mechanism to form the carbocation intermediate, more the stability of carbocation more will be the reactivity of the given compound with HBr/HC1.
-NO2 group is an electron withdrawing group and due to the -M effect, increases the stability of carbocation. Cl group at para position shows + M effect due to it, carbocation is least stable and hence, the compound (c) is the least reactive.
New answer posted
4 months ago
Contributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
(II) b > d > a > c > e
The acidic strength decreases with increasing stability of the conjugate base of the given alcohol. -NO2 group at the para position in compound (b) is the most acidic due to the -M effect of the -NO2 group.
Compound (d) has -I effect on the conjugate base, whereas the -OCH3 group has + M effect on the conjugate base and hence decreases the acidity of compounds (c) and (e).
New answer posted
4 months agoContributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
(IV) m-Chlorophenol
Phenols are more acidic than sp3 and sp2 hybridized alcohol. The m-Chlorophenol is more acidic than phenol due to the -I effect (dominated by the + R effect) of chlorine atom increasing the acidity of phenol.
New answer posted
4 months agoContributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
(IV) o-methoxy phenol
The stability of the conjugate base determines the acidic character of the compound. Higher the stability of the conjugate base, the higher is the acidic character.
Phenol, O-nitrophenol, O-methyl phenol, and O-methoxy phenol all are aromatic compounds. In aromatic compounds, the negative charge of the conjugate base charge is delocalised. The delocalisation of negative charge gives additional stability to the compound.
Ethanol is not aromatic and it cannot delocalise the negative charge formed after the H+ ion leaves the c. So,
New answer posted
4 months agoContributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
(I) C6H5OH
C6H5OH, phenol is a strong acid (due to resonance) which will react with sodium hydroxide solution in water to form sodium phenoxide and water. Phenol is more acidic than sp3 hybridized attached alcohols.
New answer posted
4 months ago
Contributor-Level 10
This is a multiple choice answer as classified in NCERT Exemplar
(II) ΘOR
The species which is the weakest acid has the strongest conjugate base. The ROH is the weakest acid among the given compounds due to the inductive effect of the alkyl group. Therefore, the strongest conjugate base is ΘOR.
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