Here are 50 Assertion and Reason questions for CBSE Class 12 Chemistry Chapter 11: "Alcohols, Phenols, and Ethers," based on the NCERT Class 12 Chemistry book. Each question includes four answer options, followed by the explanation for the correct answer.
A) Both Assertion and Reason are correct, and Reason is the correct explanation
for Assertion.
B) Both Assertion and Reason are correct, but Reason is not the correct
explanation for Assertion.
C) Assertion is correct, but Reason is incorrect.
D) Assertion is incorrect, but Reason is correct.
Assertion (A): Alcohols are more soluble in water than
hydrocarbons of similar molecular mass.
Reason (R): Alcohols can form hydrogen bonds with water
molecules, whereas hydrocarbons cannot.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols have an -OH group, which can form
hydrogen bonds with water, making them more soluble in water than hydrocarbons.
Assertion (A): Phenols are stronger acids than alcohols.
Reason (R): Phenols can donate a proton (H+) more easily due to
the resonance stabilization of the phenoxide ion.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The phenoxide ion is stabilized by resonance,
which makes phenols stronger acids compared to alcohols.
Assertion (A): Ethers are less reactive than alcohols and
phenols.
Reason (R): Ethers have an oxygen atom bonded to two alkyl or
aryl groups, which makes them less prone to nucleophilic attack.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Ethers are less reactive because the oxygen atom
is less electrophilic than in alcohols and phenols, making them less susceptible
to nucleophilic substitution.
Assertion (A): Ethanol has a lower boiling point than
ethylamine.
Reason (R): Ethylamine forms stronger hydrogen bonds due to the
presence of a nitrogen atom with a lone pair, whereas ethanol only has the -OH
group.
Answer: B) Both Assertion and Reason are correct, but Reason is
not the correct explanation for Assertion.
Explanation: Ethylamine has a lower molecular weight than
ethanol, but the presence of the nitrogen lone pair in ethylamine does not
account for its higher boiling point. The stronger hydrogen bonds in ethylamine
raise its boiling point compared to ethanol.
Assertion (A): The reaction of alcohol with hydrogen halides
proceeds via an electrophilic substitution mechanism.
Reason (R): Alcohols are nucleophilic and react with hydrogen
halides by forming a carbocation intermediate.
Answer: B) Both Assertion and Reason are correct, but Reason is
not the correct explanation for Assertion.
Explanation: The reaction proceeds via an electrophilic
substitution mechanism, but alcohols react with hydrogen halides to form
carbocations via nucleophilic substitution, not electrophilic substitution.
Assertion (A): Alcohols can be oxidized to aldehydes and
ketones.
Reason (R): Primary alcohols are oxidized to aldehydes, and
secondary alcohols are oxidized to ketones.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Primary alcohols are oxidized to aldehydes, and
secondary alcohols are oxidized to ketones due to the difference in the
structure of the alcohols.
Assertion (A): In phenol, the hydroxyl group is attached to a
benzene ring.
Reason (R): The presence of the hydroxyl group in phenol makes
it more reactive than benzene.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The hydroxyl group in phenol makes the benzene
ring more reactive, as it donates electron density to the ring, making it more
susceptible to electrophilic substitution reactions.
Assertion (A): Ethers are generally less polar than alcohols.
Reason (R): Ethers have two alkyl or aryl groups attached to an
oxygen atom, whereas alcohols have a hydroxyl group attached to an alkyl group.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols are more polar because of the -OH group,
which forms hydrogen bonds with water. Ethers have lower polarity due to the
absence of a hydrogen bond donor.
Assertion (A): The solubility of alcohols in water decreases
with increasing molecular size.
Reason (R): Larger alcohols have longer hydrocarbon chains,
which reduce their ability to form hydrogen bonds with water molecules.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: As the size of the alcohol molecule increases, the
hydrophobic nature of the alkyl chain becomes more significant, reducing its
solubility in water.
Assertion (A): Phenols are weak acids.
Reason (R): The phenoxide ion is stabilized by resonance, which
facilitates the loss of a proton.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Phenols are weak acids because the negative charge
on the oxygen atom after proton loss is delocalized through resonance, making it
easier for phenols to lose a proton.
Assertion (A): Ethers have lower boiling points than alcohols.
Reason (R): Ethers lack hydrogen bonding, which makes their
boiling points lower compared to alcohols, which can form hydrogen bonds.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols can form hydrogen bonds, which increases
their boiling points, whereas ethers cannot, leading to lower boiling points.
Assertion (A): The hydroxyl group in alcohols makes them
nucleophilic.
Reason (R): The oxygen atom in the hydroxyl group has a lone
pair of electrons that can participate in nucleophilic reactions.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The lone pair of electrons on the oxygen atom in
the hydroxyl group makes alcohols nucleophilic and capable of reacting with
electrophiles.
Assertion (A): Alcohols can be synthesized by reducing
aldehydes and ketones.
Reason (R): The reduction of aldehydes and ketones involves the
addition of hydrogen, which converts the carbonyl group to a hydroxyl group.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The reduction of aldehydes and ketones with
hydrogen leads to the formation of alcohols by reducing the carbonyl group to a
hydroxyl group.
Assertion (A): The boiling point of phenol is higher than that
of benzene.
Reason (R): Phenol can form hydrogen bonds, whereas benzene
cannot.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The ability of phenol to form hydrogen bonds
increases its boiling point compared to benzene, which lacks such interactions.
Assertion (A): Ethers are more stable than alcohols.
Reason (R): Ethers do not have an -OH group, making them less
reactive and more stable than alcohols.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The absence of an -OH group in ethers makes them
less reactive and more stable than alcohols, which have a hydroxyl group that
can undergo reactions.
Assertion (A): Alcohols are more soluble in organic solvents
than in water.
Reason (R): Alcohols contain a hydroxyl group that can form
hydrogen bonds with both organic solvents and water.
Answer: C) Assertion is correct, but Reason is incorrect.
Explanation: Alcohols are generally more soluble in water due
to hydrogen bonding with water molecules. However, they may also be soluble in
organic solvents, depending on the solvent's polarity.
Assertion (A): Ethers are used as solvents in organic
reactions.
Reason (R): Ethers are relatively inert and can dissolve a wide
range of organic compounds.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Ethers are commonly used as solvents because they
are inert and can dissolve a variety of organic compounds due to their polarity.
Assertion (A): The reaction of alcohols with sodium produces
hydrogen gas.
Reason (R): Alcohols have an -OH group, which reacts with
sodium to release hydrogen gas.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols react with sodium to produce hydrogen
gas, as the sodium displaces the hydrogen from the hydroxyl group (-OH).
Assertion (A): The oxidation of primary alcohols yields
aldehydes.
Reason (R): Primary alcohols have one alkyl group attached to
the carbonyl carbon, which makes them susceptible to oxidation.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Primary alcohols are oxidized to aldehydes due to
the presence of a hydrogen atom attached to the carbonyl carbon, making them
easy to oxidize.
Assertion (A): Ethers are often used as anesthetics.
Reason (R): Ethers have low boiling points and are volatile,
making them suitable for use as anesthetics.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Ethers like diethyl ether are volatile and have
low boiling points, which makes them suitable for use as anesthetics because
they can evaporate easily and act on the body.
Assertion (A): Phenols are more acidic than alcohols.
Reason (R): The phenoxide ion formed after deprotonation is
stabilized by resonance, whereas the alkoxide ion from alcohols is not.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The phenoxide ion formed after proton loss is
stabilized by resonance, which makes phenols stronger acids than alcohols.
Assertion (A): The reaction of alcohols with sodium produces
sodium alkoxide and hydrogen gas.
Reason (R): The sodium metal displaces the hydrogen atom from
the hydroxyl group of alcohols, forming sodium alkoxide and releasing hydrogen
gas.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Sodium reacts with alcohols, replacing the
hydrogen atom in the hydroxyl group with a sodium atom, resulting in the
formation of sodium alkoxide and hydrogen gas.
Assertion (A): Alcohols have higher boiling points than
aldehydes and ketones.
Reason (R): Alcohols can form hydrogen bonds between molecules,
while aldehydes and ketones do not have hydrogen-bonding capabilities.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols can form hydrogen bonds, which increase
their boiling points compared to aldehydes and ketones, which lack this ability.
Assertion (A): Ethers are less soluble in water than alcohols.
Reason (R): Alcohols have the ability to form hydrogen bonds
with water molecules, whereas ethers can only form dipole-dipole interactions.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols form stronger hydrogen bonds with water
compared to ethers, which can only interact through dipole-dipole interactions,
making alcohols more soluble in water.
Assertion (A): Primary alcohols can be oxidized to carboxylic
acids.
Reason (R): Primary alcohols are oxidized first to aldehydes
and then further oxidized to carboxylic acids.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Primary alcohols undergo two steps of oxidation:
first to aldehydes and then further to carboxylic acids.
Assertion (A): The -OH group in alcohols makes them polar and
hydrophilic.
Reason (R): The oxygen atom in the hydroxyl group is
electronegative, allowing it to interact with water molecules through hydrogen
bonds.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The electronegativity of oxygen in the -OH group
makes alcohols polar, and their ability to form hydrogen bonds with water makes
them hydrophilic.
Assertion (A): The boiling point of ethers is higher than that
of hydrocarbons of similar molecular weight.
Reason (R): Ethers have a polar oxygen atom, which leads to
dipole-dipole interactions, whereas hydrocarbons have only London dispersion
forces.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Ethers, due to the polar oxygen atom, experience
dipole-dipole interactions, which increase their boiling point compared to
hydrocarbons, which experience only London dispersion forces.
Assertion (A): Alcohols are less acidic than phenols.
Reason (R): The phenoxide ion formed after deprotonation is
stabilized by resonance, unlike the alkoxide ion from alcohols, which is not
stabilized.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Phenols are more acidic than alcohols because the
phenoxide ion is stabilized by resonance, while the alkoxide ion formed from
alcohols lacks such stabilization.
Assertion (A): Alcohols undergo dehydration to form alkenes in
the presence of concentrated sulfuric acid.
Reason (R): Alcohols lose a water molecule upon heating with
concentrated sulfuric acid, leading to the formation of an alkene.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The concentrated sulfuric acid removes a water
molecule from alcohols through a dehydration reaction, resulting in the
formation of an alkene.
Assertion (A): Alcohols are more reactive than ethers in
electrophilic substitution reactions.
Reason (R): The hydroxyl group in alcohols is more
electron-donating than the oxygen atom in ethers, making alcohols more reactive
towards electrophiles.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The electron-donating nature of the hydroxyl group
in alcohols makes them more reactive towards electrophilic substitution
reactions compared to ethers.
Assertion (A): Ethers are used as solvents for reactions
involving Grignard reagents.
Reason (R): Ethers are non-polar, and they stabilize Grignard
reagents by coordinating with the magnesium atom.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Ethers are non-polar and can stabilize Grignard
reagents by coordinating with the magnesium atom, making them ideal solvents for
these reactions.
Assertion (A): The oxidation of secondary alcohols produces
ketones.
Reason (R): Secondary alcohols have two alkyl groups attached
to the carbon bearing the hydroxyl group, which makes them resistant to further
oxidation.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Secondary alcohols are oxidized to ketones, and
due to the presence of two alkyl groups on the carbonyl carbon, they cannot
undergo further oxidation to carboxylic acids.
Assertion (A): The presence of the hydroxyl group makes
alcohols polar compounds.
Reason (R): The oxygen atom in the hydroxyl group has a partial
negative charge, and the hydrogen has a partial positive charge, leading to
polarity.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The polar nature of the hydroxyl group in alcohols
arises from the electronegativity difference between oxygen and hydrogen, which
gives the -OH group a dipole moment.
Assertion (A): Phenol undergoes electrophilic substitution
reactions more readily than benzene.
Reason (R): The -OH group in phenol donates electron density to
the benzene ring, making it more reactive towards electrophiles.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The electron-donating -OH group in phenol
increases the electron density of the benzene ring, making it more reactive
towards electrophilic substitution reactions compared to benzene.
Assertion (A): The reaction of alcohols with hydrogen halides
leads to the formation of alkyl halides.
Reason (R): Alcohols undergo nucleophilic substitution with
hydrogen halides, where the -OH group is replaced by a halogen atom.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols undergo nucleophilic substitution
reactions with hydrogen halides, where the hydroxyl group is replaced by a
halogen atom to form alkyl halides.
Assertion (A): Alcohols can be oxidized to carboxylic acids by
using strong oxidizing agents.
Reason (R): The hydroxyl group in alcohols makes them
susceptible to oxidation to higher oxidation states like aldehydes or carboxylic
acids.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols can be oxidized to aldehydes and further
to carboxylic acids using strong oxidizing agents due to the availability of the
hydroxyl group for oxidation.
Assertion (A): Ethyl alcohol has a lower boiling point than
glycerol.
Reason (R): Glycerol has three -OH groups, which allow it to
form more hydrogen bonds than ethyl alcohol, resulting in a higher boiling
point.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Glycerol has three hydroxyl groups, allowing it to
form more hydrogen bonds than ethyl alcohol, thus giving it a higher boiling
point.
Assertion (A): Alcohols are generally more reactive than ethers
in nucleophilic substitution reactions.
Reason (R): Alcohols contain the -OH group, which is a good
leaving group in nucleophilic substitution, while ethers do not have a good
leaving group.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols are more reactive than ethers in
nucleophilic substitution because the -OH group in alcohols can act as a leaving
group, whereas ethers do not have a similar leaving group.
Assertion (A): Alcohols undergo dehydration to form alkenes
when heated with sulfuric acid.
Reason (R): The dehydration reaction involves the removal of a
water molecule from alcohols, which leads to the formation of a double bond.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols undergo dehydration in the presence of
sulfuric acid, which results in the elimination of a water molecule and the
formation of alkenes.
Assertion (A): Alcohols can act as weak acids due to the
presence of the hydroxyl group.
Reason (R): The hydroxyl group in alcohols can donate a proton,
leading to the formation of alkoxide ions.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The -OH group in alcohols is capable of donating a
proton (H⁺), making alcohols weak acids and resulting in the formation of
alkoxide ions.
Assertion (A): Primary alcohols are more easily oxidized than
secondary alcohols.
Reason (R): Primary alcohols can be oxidized to aldehydes and
then to carboxylic acids, while secondary alcohols only form ketones.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Primary alcohols are more easily oxidized to
aldehydes and carboxylic acids, while secondary alcohols form ketones, which are
resistant to further oxidation.
Assertion (A): Alcohols are used as solvents in many chemical
reactions.
Reason (R): The -OH group in alcohols makes them polar, which
allows them to dissolve many ionic and polar compounds.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The polar nature of alcohols allows them to
dissolve a wide range of ionic and polar compounds, making them useful solvents
in many chemical reactions.
Assertion (A): Ethers are more stable than alcohols.
Reason (R): Ethers lack a reactive -OH group and are less prone
to oxidation compared to alcohols.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Ethers are more stable than alcohols because they
lack a reactive -OH group and are less prone to oxidation.
Assertion (A): Alcohols can be dehydrated to form alkenes using
concentrated sulfuric acid.
Reason (R): Concentrated sulfuric acid acts as both a
dehydrating agent and a catalyst in the dehydration reaction of alcohols.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Concentrated sulfuric acid removes water from
alcohols and acts as a catalyst to promote the formation of alkenes through
dehydration.
Assertion (A): The boiling points of alcohols are higher than
those of hydrocarbons of similar molecular weight.
Reason (R): Alcohols can form hydrogen bonds, which increase
the energy required to break intermolecular forces and raise the boiling point.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Alcohols can form hydrogen bonds, which increase
the boiling point compared to hydrocarbons, which only experience weaker London
dispersion forces.
Assertion (A): Phenol is a stronger acid than alcohol.
Reason (R): The phenoxide ion formed after deprotonation is
stabilized by resonance, while the alkoxide ion from alcohols is not.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The phenoxide ion is stabilized by resonance,
making phenol a stronger acid than alcohol, where the alkoxide ion lacks such
stabilization.
Assertion (A): Alcohols are polar and can form hydrogen bonds.
Reason (R): The oxygen atom in the hydroxyl group of alcohols
is electronegative and can form hydrogen bonds with other molecules.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The electronegativity of oxygen in the hydroxyl
group makes alcohols polar and enables them to form hydrogen bonds, which
influence their physical properties.
Assertion (A): Alcohols can be dehydrated to form alkenes when
heated with zinc dust.
Reason (R): Zinc dust provides the necessary heat and acts as a
catalyst in the dehydration of alcohols to form alkenes.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Zinc dust provides heat for the dehydration
reaction and can catalyze the formation of alkenes from alcohols.
Assertion (A): Phenols have a higher boiling point than
alcohols.
Reason (R): Phenols have a hydroxyl group attached to an
aromatic ring, and the presence of the aromatic ring leads to stronger
intermolecular forces compared to alcohols.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: Phenols have stronger intermolecular forces due to
the aromatic ring, which results in a higher boiling point compared to alcohols.
Assertion (A): Alcohols are good solvents for ionic compounds.
Reason (R): Alcohols are polar and can solvate ions, making
them suitable for dissolving ionic compounds.
Answer: A) Both Assertion and Reason are correct, and Reason is
the correct explanation for Assertion.
Explanation: The polarity of alcohols allows them to dissolve
ionic compounds by solvating the ions and forming strong interactions.