Alcohols Phenols and Ethers: Chemistry Free Online Mock Test 1

Explanation: When alkanes are halogenated by free radicals, they form a mixture of haloalkanes rather than alcohols. Alcohols can be made from alkenes through acid catalysed hydration, and hydroboration-oxidation, and from aldehyde reduction.

Explanation: In the presence of aqueous NaOH, trialkyl boranes are oxidised by hydrogen peroxide to produce alcohol. This conversion does not require diborane, although it is required for the creation of trialkyl boranes.

Explanation: When phenol is treated with bromine water, a white precipitate is formed, which is 2,4,6-Tribromophenol.

Solution: (c) Compound (A) i.e., phenol and compound (D) i.e., a derivative of phenol cannot be considered as aromatic alcohol. As phenol is also known as, carbolic acid cannot be considered as aromatic alcohol.
Compound (B) and (C), -OH group is bonded to sp³ hybridised carbon which in turn is bonded to benzene ring

Solution: (b) 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 and in o-methoxyphenol, electron releasing group (-CH₃-OCH₃)

Solution: (b) Weakest acid has the strongest conjugate base. Since R-OH is the weakest acid, therefore, RO is the strongest base.

Explanation: The oxidation of secondary alcohols by a nascent oxygen atom [O] yields the ketone molecule.

Solution: (d) Monochlorination of toluene in sunlight gives benzyl chloride. On hydrolysis with aq. NaOH, benzyl chloride shows nucleophilic substitution reaction to give benzyl alcohol.

Solution: (a) Phenol being more acidic reacts with sodium hydroxide solution in water to give sodium phenoxide which is resonance stabilized.
Alcohols are very weak acids.
C₆H₅OH + NaOH -> C₆H₅ONa + H₂O

Explanation: –CH₃ group in o-cresol is electron donating, decreases acidity. –NO₂ group in o-nitrophenol is electron withdrawing, stabilizes phenoxide ion and increases acidity.

Explanation: Invertase converts sucrose into glucose and fructose, then zymase converts them into ethanol and CO₂.

Solution: (a) Boiling point increases with increase in molecular mass of the alcohols. Among isomeric alcohols 1° alcohols have higher boiling points than 2° alcohols. Thus, correct order is:
Propan-l-ol < butan-2-ol < butan-l-ol < pentan-l-ol.

Solution: (b, c) In benzylic alcohols, the -OH group is attached to a sp3 hybridised carbon atom next to an aromatic ring. In compounds (a) and (d), the -OH group is attached to a sp3 hybridised carbon atom but this carbon is not attached to the benzene ring.
On the other hand, in compounds (a) and (c), the -OH group is attached to a sp3 hybridised carbon atom next to an aromatic ring.

Explanation: Water is more acidic than alcohol due to absence of +I effect. Alkyl group in alcohol decreases acidity. Terminal alkyne is least acidic among these.

Solution: (d) Alcohols are less acidic than phenol. Further electron withdrawing group (like – Cl) increases the acidity of phenol, therefore, m-chlorophenol is most

Explanation: On heating with water, benzene diazonium chloride undergoes hydrolysis, replacing diazonium group with –OH to form phenol with release of N₂ gas.

Explanation: Phenol is highly activated due to –OH group, so bromination occurs at ortho and para positions forming 2,4,6-tribromophenol as a white precipitate.

Solution: CrO₃ in anhydrous medium, PCC and heating in presence of Cu (dehydrogenation) will oxidize primary alcohols to aldehydes. KMnO₄ will further oxidize it to acid.

Explanation: Alkyl groups show +I effect and increase electron density on oxygen, making O–H bond stronger. More alkyl groups reduce reactivity, so primary alcohol reacts fastest.

Explanation: Propan-2-one reacts with Grignard reagent (CH₃MgI) to form addition product which on hydrolysis gives tert-butyl alcohol.

Explanation: In phenol, oxygen is attached to sp² carbon which forms stronger bond than sp³ carbon in alcohol.

Explanation: Tertiary alkyl halides favor elimination over substitution, so alkene is formed instead of ether.

Explanation: CO₂ is linear so bond dipoles cancel. Ether has bent structure so dipoles do not cancel, making it polar.

Explanation: Phenoxide ion has negative charge delocalized over ring, increasing electron density and making it more reactive for CO₂ attachment.

Explanation: Phenol reacts with NaOH to form sodium phenoxide, then CO₂ gives salicylic acid, which on acetylation forms aspirin.

Explanation: In phenol, electron withdrawing benzene ring reduces polarity of C–O bond, so dipole moment is less than methanol.

Explanation: In aqueous medium, phenol is highly activated giving tribromination, while in non-aqueous medium controlled mono substitution occurs.