CBSE Class 12 Chemistry Amines MCQs Set 06

MCQs

Question. \( \text{CH}_3\text{CONH}_2 \) on reaction with \( \text{NaOH} \) and \( \text{Br}_2 \) in alcoholic medium gives:
(a) \( \text{CH}_3\text{CH}_2\text{NH}_2 \)
(b) \( \text{CH}_3\text{CH}_2\text{Br} \)
(c) \( \text{CH}_3\text{NH}_2 \)
(d) \( \text{CH}_3\text{COONa} \)
Answer: (c) \( \text{CH}_3\text{NH}_2 \)

Question. Propanamide on reaction with bromine in aqueous \( \text{NaOH} \) gives:
(a) Propanamine
(b) Ethanamine
(c) N-Methyl ethanamine
(d) Propanenitrile
Answer: (b) Ethanamine

Question. IUPAC name of product formed by reaction of methyl amine with two moles of ethyl chloride
(a) N,N-Dimethylethanamine
(b) N,N-Diethylmethanamine
(c) N-Methyl ethanamine
(d) N-Ethyl - N-methylethanamine
Answer: (d) N-Ethyl - N-methylethanamine

Question. Which of the following reagents would not be a good choice for reducing an aryl nitro compound to an amine?
(a) \( \text{H}_2 \)(excess)/Pt
(b) \( \text{LiAlH}_4 \) in ether
(c) Fe and HCl
(d) Sn and HCl
Answer: (b) \( \text{LiAlH}_4 \) in ether

Question. The best reagent for converting 2–phenylpropanamide into 2-phenylpropanamine is _____.
(a) excess \( \text{H}_2 \)
(b) \( \text{Br}_2 \) in aqueous \( \text{NaOH} \)
(c) Iodine in the presence of red phosphorus
(d) \( \text{LiAlH}_4 \) in ether
Answer: (d) \( \text{LiAlH}_4 \) in ether

Question. Hinsberg’s reagent which is used to test amines is
(a) Benzene sulphonamide
(b) Benzene diazonium chloride
(c) Benzene sulphonyl chloride
(d) Acetanilide
Answer: (c) Benzene sulphonyl chloride

Question. The best method for preparing primary amines from alkyl halides without changing the number of carbon atoms in the chain is:
(a) Hoffmann Bromamide reaction
(b) Gabriel phthalimide synthesis
(c) Sandmeyer reaction
(d) Reaction with \( \text{NH}_3 \)
Answer: (b) Gabriel phthalimide synthesis

Question. The correct IUPAC name for \( \text{CH}_2 = \text{CHCH}_2\text{NHCH}_3 \) is:
(a) Allylmethylamine
(b) 2-amino-4-pentene
(c) 4-aminopent-1-ene
(d) N-methylprop-2-en-1-amine
Answer: (d) N-methylprop-2-en-1-amine

Question. Which of the following is a \( 3^\circ \) amine?
(a) 1-methylcyclohexylamine
(b) Triethylamine
(c) tert-butylamine
(d) N-methylaniline
Answer: (b) Triethylamine

Question. Methylamine reacts with \( \text{HNO}_2 \) to form _________.
(a) \( \text{CH}_3 - \text{O} - \text{N} = \text{O} \)
(b) \( \text{CH}_3 - \text{O} - \text{CH}_3 \)
(c) \( \text{CH}_3\text{OH} \)
(d) \( \text{CH}_3\text{CHO} \)
Answer: (c) \( \text{CH}_3\text{OH} \)

Question. The gas evolved when methylamine reacts with nitrous acid is:
(a) \( \text{NH}_3 \)
(b) \( \text{N}_2 \)
(c) \( \text{H}_2 \)
(d) \( \text{C}_2\text{H}_6 \)
Answer: (b) \( \text{N}_2 \)

Question. Arrange the following in increasing order of basic strength: Aniline, p-nitroaniline and p-toluidine
(a) Aniline < p-Nitroaniline < p-Toluidine
(b) Aniline < p-Toluidine < p-Nitroaniline
(c) p-Toluidine < p-Nitroaniline < Aniline
(d) p-Nitroaniline < Aniline < p-Toluidine
Answer: (d) p-Nitroaniline < Aniline < p-Toluidine

Question. Which of the following species are involved in the carbylamine test?
(a) R—NC
(b) \( \text{COCl}_2 \)
(c) \( \text{NaNO}_2 + \text{HCl} \)
(d) All of the options
Answer: (a) R—NC

Question. Which of the following amines can be prepared by Gabriel synthesis?
(a) Isobutyl amine
(b) Toluene
(c) N-methylbenzylamine
(d) Aniline
Answer: (a) Isobutyl amine

Assertion and Reason Based MCQs

Directions: In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as:
(a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.

Question. Assertion (A): Acylation of amines gives a monosubstituted product whereas alkylation of amines gives poly substituted product.
Reason (R): Acyl group sterically hinders the approach of further acyl groups.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (c) (A) is true, but (R) is false.

Question. Assertion (A): Acetanilide is less basic than aniline.
Reason (R): Acetylation of aniline results in decrease of electron density on nitrogen.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (a) Both (A) and (R) are true, and (R) is the correct explanation of (A).

Question. Assertion (A): N, N-Diethylbenzene sulphonamide is insoluble in alkali.
Reason (R): Sulphonyl group attached to nitrogen atom is strong electron withdrawing group.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (a) Both (A) and (R) are true, and (R) is the correct explanation of (A).

Question. Assertion (A): Aromatic \( 1^\circ \) amines can be prepared by Gabriel Phthalimide synthesis.
Reason (R): Aryl halides do not undergo nucleophilic substitution with anion formed by phthalimide.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (d) (A) is false, but (R) is true.

Question. Assertion (A): Solubility of amines in water decreases with increase in molar mass.
Reason (R): Intermolecular H bonds formed by the higher amines are weaker.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (c) (A) is true, but (R) is false.

Case-based MCQs

I. Read the passage given below and answer the following questions:
Greater is the stability of the substituted ammonium cation, stronger should be the corresponding amine as a base. Thus, the order of basicity of aliphatic amines should be: primary > secondary > tertiary, which is opposite to the inductive effect based order. Secondly, when the alkyl group is small, like \( -\text{CH}_3 \) group, there is no steric hindrance to H-bonding. In case the alkyl group is bigger than \( \text{CH}_3 \) group, there will be steric hinderance to H-bonding. Therefore, the change of nature of the alkyl group, e.g., from \( -\text{CH}_3 \) to \( -\text{C}_2\text{H}_5 \) results in change of the order of basic strength.
In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

Question. Assertion (A): \( (\text{CH}_3)_2\text{NH} > \text{CH}_3\text{NH}_2 > (\text{CH}_3)_3\text{N} > \text{NH}_3 \) is the order of basic strength in case of methyl substituted amines.
Reason (R): The inductive effect, solvation effect and steric hindrance of the alkyl group decide the basic strength of alkyl amines in the aqueous state.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (a) Assertion and reason both are correct statements and reason is correct explanation for assertion.

Question. Assertion (A): \( (\text{C}_2\text{H}_5)_2\text{NH} > (\text{C}_2\text{H}_5)_3\text{N} > \text{C}_2\text{H}_5\text{NH}_2 > \text{NH}_3 \) is the order of basic strength in case of ethyl substituted amines.
Reason (R): The change of nature of the alkyl group, does not result in change of the order of basic strength.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (c) Assertion is correct statement but reason is wrong statement.

Question. Assertion (A): Greater is the stability of the substituted ammonium cation, stronger is the corresponding amine as a base.
Reason (R): The order of basicity of aliphatic amines is: primary > secondary > tertiary.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (c) Assertion is correct statement but reason is wrong statement.

Question. Assertion (A): Amines behave as a Lewis base.
Reason (R): Amines have an unshared pair of electrons on nitrogen atom.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (a) Assertion and reason both are correct statements and reason is correct explanation for assertion.

II. Read the passage given below and answer the following questions:
Benzene ring in aniline is highly activated. This is due to the sharing of lone pair of nitrogen with the ring which results in increase in the electron density on the ring and hence facilitates the electrophilic attack. The substitution mainly takes place at ortho and para positions because electron density is more at ortho and para positions. On reaction with aqueous bromine all the ortho and para positions get substituted resulting in the formation of 2,4,6-tribromoaniline. To get a monobromo compound, the amino group is acetylated before bromination. After bromination, the bromoacetanilide is acid hydrolysed to give the desired halogenated amine.
In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

Question. Assertion (A): Benzene ring of aniline is highly deactivated.
Reason (R): In aniline, the sharing of lone pair of nitrogen with the ring increases the electron density on the ring.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (d) Assertion is wrong statement but reason is correct statement.

Question. Assertion (A): In aniline \( -\text{NH}_2 \) group facilitates the electrophilic attack.
Reason (R): It is due to decrease in electron density on the ring.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (c) Assertion is correct statement but reason is wrong statement.

Question. Assertion (A): In aniline, the substitution mainly takes place at ortho and para positions.
Reason (R): The electron density is more at ortho and para positions.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (a) Assertion and reason both are correct statements and reason is correct explanation for assertion.

Question. Assertion (A): The amino group of aniline is acetylated before bromination.
Reason (R): It is due to the strong deactivating effect of \( -\text{NH}_2 \) group.
(a) (a)
(b) (b)
(c) (c)
(d) (d)
Answer: (c) Assertion is correct statement but reason is wrong statement.

III. Read the passage given below and answer the following questions:
The main problem encountered during electrophilic substitution reactions of aromatic amines is that of their very high reactivity. Substitution tends to occur at ortho and para positions. To prepare monosubstituted aniline derivative, the activating affect of \( -\text{NH}_2 \) group be controlled. This can be done by protecting the \( -\text{NH}_2 \) group by acetylation with acetic anhydride, then carrying out the desired substitution followed by hydrolysis of the substituted amide to the substituted amine.

Question. Why is the activating effect of \( -\text{NHCOCH}_3 \) group in the above reaction less than the activating effect of amino group?
(a) Due to mesomeric effect of benzene ring.
(b) Due to inductive effect of alkyl group.
(c) Due to resonance effect of acetanilide.
(d) All of the options
Answer: (c) Due to resonance effect of acetanilide.

Question. Aniline is a resonance hybrid of:
(a) 3 resonating structures
(b) 6 resonating structures
(c) 2 resonating structures
(d) 5 resonating structures
Answer: (d) 5 resonating structures