Chemistry NCERT Exemplar Solutions Class 12th Chapter Eleven

This is a short answer type question as classified in NCERT Exemplar

Increasing order of acidity is: ethanol < water < phenol.
This is because the phenoxide ion obtained after the removal of H⁺ is resonance stabilised, while the ethoxide ion obtained after the removal of H⁺ is destabilised by +1 effect of ethyl group. Thus phenol is a stronger acid than ethanol.
Now, ethanol is a weaker acid than water because the electron releasing ethyl group increases the ethanol density on oxygen and consequently the proton will not be released easily. There is no such effect is water.

This is a short answer type question as classified in NCERT Exemplar

Due to the presence of intermolecular H- bonds in alcohol the energy required to break H – bonds is more than the energy required to break simple dipole bonds present in ethers . Thus, the boiling point of alcohol is higher than the boiling point of ethers.

This is a short answer type question as classified in NCERT Exemplar

The electron withdrawing group (-NO₂), withdraws electrons and disperses the negative charge. Therefore, -NO₂ group stabilizes the phenoxide ion. Hence p-nitrophenol is more acidic than phenol.

This is a short answer type question as classified in NCERT Exemplar

The occurrence of intermolecular hydrogen bonds due to the H- bonds in alcohol compounds play a major role . With the increasing number of alkyl groups the molecular mass increases due to which the polar nature of these compounds get suppressed . Hence, the solubility factor of alcohols is indirectly proportional to the molecular mass.

This is a short answer type question as classified in NCERT Exemplar

The bond angle C—O—H in alcohols is less than tetrahedral angle because of the repulsion between the lone pairs present on the oxygen atom, which pushes the bond C—O—H closer. Therefore,   C—O—H bond angle in alcohols is slightly less than the tetrahedral angle.

In  ethers, the lone pairs on oxygen atoms are also present but the two bulky alkyl groups also have repulsive force which increases the C—O—C bond angle. Therefore,   the C—O—C bond angle in ether is slightly greater than tetrahedral angle .

This is a short answer type question as classified in NCERT Exemplar

Ethers are prepared by Williamson synthesis by the reaction of alkyl halide with the stadium alkoxide. But this is not possible in case of di-tert-butyl ether. In case of preparation of di-tert-butyl ether, tert-butyl halide must react with sodium tert-butoxide. Alkoxides are nucleophiles but they are strong bases as well, due to which elimination is favoured instead of substitution and leads to the formation of 2-methylprop-1-ene.

This is a short answer type question as classified in NCERT Exemplar

In phenol, the electron pairs on oxygen atom of -OH group are in conjugation (or resonance) with phenyl ring which decreases the polarity of the C-OH bond whereas in methanol the polarity of C-OH bond is more due to electron releasing group of -CH₃.

This is a short answer type question as classified in NCERT Exemplar

Phenoxide ion is more reactive than phenol to electrophilic aromatic substitution reaction  due to the more in electron density of  phenoxide ion and hence, phenoxide ion easily undergoes the electrophilic substitution reaction than phenol by the weak CO₂ electrophile.