CBSE Class 12 Chemistry Alcohols Phenols and Ethers Assignment

Question. Acetone on treatment with CH₃ −Mg − I and on further hydrolysis gives:
a. Isopropyl alcohol
b. Primary alcohol
c. Acetic acid
d. 2-methyl 2-propanol
Answer : D

Question. Acetyl bromide reacts with excess of CH₃ MgI followed by treatment with a saturated solution of NH₄ Cl gives:
a. 2-methyl-2-propanol
b. Acetamide
c. Acetone
d. Acetyl iodide
Answer : A

Question. Methyl alcohol can be distinguished from ethyl alcohol using:
a. Fehling solution
b. Schiff's reagent
c. Sodium hydroxide and iodine
d. Phthalein fusion test
Answer : C

Question. Which gas is eliminated in fermentation?
a. O₂
b. CO₂
c. N₂
d. H₂
Answer : B

Question. In the reaction alkali Ar −OH + Rx ^alkali→ A, A is:
a. An aldehyde
b. An aryl chloride
c. An ether
d. A ketone
Answer : C

Question. The compound formed when ethyl bromide is heated with dry silver oxide is:
a. Dimethyl ether
b. Diethyl ether
c. Methyl alcohol
d. Ethyl alcohol
Answer : B

Question. The reagent used for the preparation of higher ether from halogenated ethers is:
a. conc. H₂SO₄
b. Sodium alkoxide
c. Dry silver oxide
d. Grignard reagent
Answer : D

Question. For phenol, which of the following statements is correct?
a. It is insoluble in water?
b. It has lower melting point compared to aromatic hydrocarbons of comparable molecular weight
c. It has higher boiling point than toluene
d. It does not show acidic property
Answer : C

Question. Commercially methanol is prepared by:
a. Reduction of CO in presence of ZnO.Cr₂O₃
b. Methane reacts with water vapours at 900°C in presence of Ni catalyst
c. Reduction of HCHO by LiAlH₄
d. Reduction of HCHO by aqueous NaOH
Answer : A

Question. the above sequence X can be:
a. H₂ / Ni
b. 4 NaBH
c. K₂Cr₂O₇ /H⁺
d. Both a.and b.
Answer : B

Question. Methylphenyl ether can be obtained by reacting:
a. Phenolate ions and methyl iodide
b. Methoxide ions and bromobenzene
c. Methanol and phenol
d. Bromo benzene and methyl bromide
Answer : A

Question. In which case methyl-t-butyl ether is formed?
a. (C₂H₃)₃ CONa + CH₃Cl
b. (CH₃)₃ CONa + CH₃Cl
c. (CHH₃)₃ CONa + C₂H₅Cl
d. (CH₃)₃ CONa + CH₃Cl
Answer : B

Question. Read the following statements carefully:
a. A secondary alcohol on oxidation gives a ketone
b. Ethanol reacts with conc. H₂SO₄ at 180°C to yield ethylene
c. Methanol reacts with iodine and sodium hydroxide to give a yellow precipitate of iodoform
d. Hydrogen gas is liberated when sodium is added to alcohol. Select the correct statements from the above set:
a. A, B
b. C, D
c. A, B, D
d. A, C, D
Answer : C

Question. Final product formed on reduction of glycerol by hydroiodic acid is:
a. Propane
b. Propanoic acid
c. Propene
d. Propyne
Answer : C

Question. Which of the following explains the viscous nature of glycerol?
a. Covalent bonds
b. Hydrogen bonds
c. Vander Wall's forces
d. Ionic forces
Answer : B

Question. From Williamson’s synthesis preparation of which of following is possible?
a. Only symmetrical ethers
b. Only symmetrical ethers
c. Both types
d. None of these
Answer : C

Question. What is obtained when chlorine is passed in boiling toluene and product is hydrolysed?
a. o-Cresol
b. p-Cresol
c. 2, 4-Dihydroxytoluene
d. Benzyl alcohol
Answer : D

Question. The reagent used for the dehydration of an alcohol is:
a. Phosphorus pentachloride
b. Calcium chloride
c. Aluminium oxide
d. Sodium chloride
Answer : C

Question. The alcohol that produces turbidity immediately with ZnCl₂ + conc. HCl at room temperature:
a. 1-hydroxybutane
b. 2-hydroxybutane
c. 2-hydroxy-2-methylpropane
d. 1-hydroxy-2-methylpropane
Answer : C

Question. The alcohol which easily reacts with conc. HCl is?
a. CH₃ −CHOH −CH₂ −CH₃
b. (CH₃)₃ − C −OH
c. CH₃ − CH −CH₂ −CH₂ −OH
d. (CH₃)₃ −CH−CH₂OH
Answer : B

Question. A compound that easily undergoes bromination is:
a. Phenol
b. Toluene
c. Benzene
d. Benzoic acid
Answer : A

Question. Which of the following methods is/are not the industrial methods to prepare methanol?
a. catalytic reduction of carbon monoxide in presence of ZnO − Cr₂O₃
b. reacting methane with steam at 900°C with a Ni catalyst
c. reducing formaldehyde with lithium aluminium hydride
d. reacting formaldehyde with aqueous sodium hydroxide solution
Answer : B, C, D

Question. Which of the following reagent (s) or test (s), can be used to distinguish 2 methyl propanol and 2-methyl propanol – 2?
a. I₂ / NaOH
b. HCl/anhyd. ZnCI₂
c. Victor-Meyer test
d. oxidation with Cu at 573 K
Answer : B, C, D

Question. When rectified spirit and benzene are distilled together, the first fraction obtained is?
a. A ternary azeotrope
b. Absolute alcohol
c. A binary azeotrope
d. Denatured spirit
Answer : A

Question. Which of the following is most acidic?
a. Phenol
b. Benzyl alcohol
c. m-chlorophenol
d. Cyclohexanol
Answer : C

Question. Which is not correct?
a. Phenol is more acidic than acetic acid
b. Ethanol is less acidic than phenol
c. Ethanol has lower boiling point than ethane
d. Ethyne is a non-linear molecule
Answer : A

Question. Glycerol is used in the manufacture of:
a. Dynamite
b. Varnish
c. Paints
d. Soft drinks
Answer : A

Question. Alcoholic fermentation is brought about by the action of:
a. CO₂
b. O₂
c. Invertase
d. Yeast
Answer : D

Question. In order to make alcohol undrinkable pyridine and methanol are added to it. The resulting alcohol is called:
a. Power alcohol
b. Proof spirit
c. Denatured spirit
d. Poison alcohol
Answer : C

Question. Main constituent of dynamite is:
a. Nitrobenzene
b. Nitroglycerine
c. Picric acid
d. TNT
Answer : B

Question. The Bouveault-Blanc reduction involves:
a. C₂H₅OH/ Na
b. LiAlH₄
c. C₂H₅MgX⁻
d. Zn / HCl
Answer : A

Question. Which is used as antifreeze?
a. Glycol
b. Ethyl alcohol
c. Water
d. Methanol
Answer : A

Question. Alkenes convert into alcohols by:
a. Hydrolysis by dil. H₂SO₄
b. Hydration of alkene by alkaline KMnO₄
c. Hydrolysis by water vapours and conc. H₂SO₄
d. Hydration of alkene by aqueous KOH
Answer : B, C

Question. The following ether, when treated with HI produces:

Answer : A, D

Question. Which of the following reactions can be used to prepare methyl phenyl ether?
a. reacting sodium phenoxide with methyl chloride
b. reacting phenol with diazomethane (CH₂ N₂ )
c. reacting sodium methoxide with chlorobenzene
d. reacting C₆H₅ OMgCl with chloromethane
Answer : A, B

Question. Carbinol is:
a. C₂H₅OH
b. CH₃OH
c. (CH₃)₂ CHOH
d. CH₃CH₂CH(OH)CH₃
Answer : B

Question. Structure of compound X is:

Than which of the following statements are correct?
a. X have two stereoisomers
b. All stereomers of X have the same melting point
c. X reaction with SOCl₂ followed by alcoholic KOH product E which containing 8π bonds
d. None of these
Answer : A, B, C

Question. An organic compound X of molecular formula C₄H₁₀O undergoes oxidation to give a compound Y of molecular formula C₄H₈O₂ .X could be:
a. CH₃CH₂CH₂CHH₂OH
b. CH₃CH₂CH(OH)CH₃
c. (CH₃)₂ CHCH₂OH
d. (CH₃)₃ COH
Answer : A, C

Question. Phenol has higher pka value than:
a. acetic acid
b. p-methoxy phenol
c. p-nitrophenol
d. ethanol
Answer : A, C

Question. Wood spirit is known as:
a. Methanol
b. Ethanol
c. Acetone
d. Benzene
Answer : A

1. Haloalkanes undergo nucleophilic substitution reaction readily than haloarenes.

Answer : (aLlow bond dissociation enthalpy of R-X bond due to low s- character of C SP³

(b) Stability of carbocation by hyper conjugation of neighboring alkyl groups.

 

2. The b.pt of isomeric haloalkanes decreases increasing in branching of carbon chains.

Answer : As branching increases molecules becomes more compact and acquires a low surface area . Since strength of Vander waals forces are proportional to area of contact

between molecules,attractive forces decreases with branching.

 

3. Alcohols have higher boiling boint compared to hydrocarbons, ethers and halo compounds of comparable mass.

Answer : Due to presence of inter molecular H-bonding,which is either absent or very weak in other molecules.

 

4. Phenol is more acidic than alcohol

 

 

The phenoxide ion is resonance stabilized due to (-) R effect of benzene ring. The alkoxide ion is less stable due to (+) I effect of –R group.

 

5. Aldehydes are more than reactives than ketones towards nucleophilic addition reactions.

Answer : (a) inductive effect of R groups reduces the electrophilicity of the C atom of carbonyl group in ketones

(b) steric hindrance: the approaching nucleophile suffers greater repulsion due to presence of two bulky-R groups in ketones.

 

6. Carboxylic acids have higher boiling points than aldehydes, ketones and alcohols of comparable molecular masses.

Answer : The C.A molecules form dimers which do not separate into monomers even in vapour phase.

 

7. Gabriel Phthalimide synthesis is not suitable for preparation of secondary and tertiary amines.

Answer : Since the reaction involves Sn2 mechanism, only a primary alkyl group can approach the sterically hindered Phthalimide ring .

 

8 pKb of aniline is more than that of methylamine.
Answer : Since the lone pair on the N-atom remains in conjugation with the benzene ring and is unavailable for donation. The basic character of methylamine is enhanced due to +I effect of –CH3 group.

9 Aniline does not undergo Friedel Crafts reaction.
Answer : Aniline is basic and reacts with anhyd. AlCl3 to form a salt which deactivates 6the benzene ring towards electrophilic substitution.

10 During esterification, water must be removed as soon as it is formed. H+
Answer : RCOOH + R’OH RCOOR’ + H2O If the by-product is not removed, it will cause backward reaction. The ester formed will breakdown giving poor yield.

LEVEL-2 QUESTIONS

Q1) Although phenoxide ion hasmore no. of resonating structures than carboxylate ion , even though carboxylic acid is a stronger acid why ?
Answer : The phenoxide ion has non equivalent resonance structures in which–vecharge is at less electronegativeC atom and +ve charge as at more electronegative O-atom.
Incarboxylate ion –ve charge is delocalized on two electronegative O-atoms hence resonance is more effective and a stronger acid.