Amines

Class 12th Chemistry – 13 Amines MCQs

Aniline reacts with hydrochloric acid to form ____.

Correct! Wrong!

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Aniline reacts with hydrochloric acid to form anilinium chloride. Amines, being basic in nature, react with acids to form salts.

Nitriles, on reduction with ____, produce primary amines.

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Nitriles, on reduction with LiAlH4, produce primary amines. The other options sodium borohydride is used for reduction reaction. Sodium cyanoborohydride and sodium triacetoxyborohydride are also metal hydrides used for reductive amination.

The order of reactivity of halides with amines is ____.

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The order of reactivity of halides with amines is RI > RBr > RCl. The reactivity of the halides can be explained based on the electronegativity of the halogen atoms.

Aniline is more stable than ____.

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Aniline is more stable than anilinium ion. Anilinium ion can have only two resonating structures. Greater the number of resonating structure, greater is the stability. Since aniline has five resonating structures, it is more stable than anilinium ion.

The order of basicity of aliphatic amines is ____.

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The order of basicity of aliphatic amines is 1o > 2o > 3o. The greater the size of the ion, lesser will be the solvation and the less stabilised is the ion. Greater the stability of the substituted ammonium cation, stronger would be the corresponding amine as a base. Hence, the order of basicity of aliphatic amines is 1o >2o >3o.

Aromatic amines are ____ bases than ammonia, due to the ____ nature of the aryl group.

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Aromatic amines are weaker bases than ammonia, due to the electron withdrawing nature of the aryl group.

Complete the following reaction. RCONH2 +? + 4NaOH → R-NH2 +? + ? +2H2O

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The complete reaction is: RCONH2 + Br2 + 4NaOH → R-NH2 + Na2CO3 + 2NaBr + 2H2O

The IUPAC name of NH2−CH2−CH = CH2 is ____.

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The IUPAC name of NH2-CH2-CH=CH2 is prop-2-ene-1-amine.The common name of this compound is allylamine.

There are ____possible resonance hybrid structures for aniline.

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There are five possible resonance hybrid structures for aniline.

4-Bromobenzenamine is also known as ____.

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4-Bromobenzenamine is also known as 4-Bromoaniline.The prefix ortho signifies a 1, 2-disubstituted benzene ring, meta signifies 1, 3-disubstitution, and para signifies 1, 4-disubstitution.

In Hoffmann bromamide degradation reaction, migration of an alkyl or aryl group takes place from ____ carbon of the amide to the ____ atom.

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In Hoffmann bromamide degradation reaction, migration of an alkyl or aryl group takes place from carbonyl carbon of the amide to the nitrogen atom.

Amine salts are ____ in water but ____ in organic solvents like ____.

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Amine salts are soluble in water but insoluble in organic solvents like ether. Tetrahydrofuran (THF), hexane, etc. are organic solvents with different polarities. THF is more polar than hexane. Few amine salts are soluble in excess polar solvents and insoluble in less polar solvents.

Amines have an unshared pair of electrons on nitrogen atom due to which they behave as ____.

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Amines have an unshared pair of electrons on nitrogen atom due to which they behave as Lewis base. A Lewis base is often a Bronsted–Lowry base, as it can donate a pair of electrons to proton. The proton is a Lewis acid, as it can accept a pair of electrons. A Bronsted–Lowry acid is a proton donor, not an electron-pair acceptor. Any substance that accepts lone pair of electrons is a Lewis acid.

Separation of amines from the non basic organic compounds is possible due to the ____ nature of amine salts in ____.

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Separation of amines from the non basic organic compounds is possible due to the insoluble nature of amine salts in organic solvents.

The greater the size of the ion, ____ will be the solvation and the ion is ____ stabilised.

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The greater the size of the ion, lesser will be the solvation and the ion is less stabilised.

Basic character of amines can be better understood in terms of their ____ and ____ values.

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Basic character of amines can be better understood in terms of their Kb and pKb values. Kb and Ka are equilibrium constants of base and acid respectively. pKb and pKa are used to define the strength of base and acid respectively. To avoid a negative value for the equilibrium constant, the negative of logarithm is used. Hence, -logKa = pKa and -logKb = pKb.

____ the value of Kb or ____ the value of pKb, stronger is the base.

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Larger the value of Kb or smaller the value of pKb, stronger is the base.

The order of basicity of amines in the gaseous phase is ____.

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The order of basicity of amines in the gaseous phase is 3o amine >2o amine >1o amine > NH3. The basic nature of aliphatic amines should increase with increase in the number of alkyl groups, as it stabilises the cation formed by the dispersal of the positive charge due to the +I effect of the alkyl group.

In arylamines, – NH2 group is directly attached to the ____ ring.

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In arylamines, –NH2 group is directly attached to the benzene ring.

Nitro compounds are reduced to amines by passing ____ gas in the presence of finely divided ____.

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Nitro compounds are reduced to amines by passing hydrogen gas in the presence of finely divided palladium. Nitrogen and argon are inert gases. Metals like palladium, platinum and nickel distributed over finely divided carbon are pyrophoric catalysts. Hence, reactions with these catalysts are performed under inert gas atmosphere and oxygen is not advised. Hydrogen is required for the reduction reactions.

Free primary amine can be obtained from the quaternary ammonium salt, by treatment with a strong base ____.

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Free primary amine can be obtained from the quaternary ammonium salt, by treatment with a strong base NaOH. The other bases K2CO3, Na2CO3, NaHCO3, are weak bases compared to NaOH.

In IUPAC system, amines are named as ____.

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In IUPAC system, amines are named as alkanamine.

The common name of N, N-dimethylmethanamine is ____.

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The common name of N, N-Dimethylmethanamine is trimethylamine.

Pick out the correct statement regarding Gabriel phthalimide synthesis.

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The correct statement is, 'Potassium phthalimide, on heating with alkyl halide gives N-alkylphthalimide.' Option A - Gabriel synthesis is used for the preparation of primary amines. Option C - N-Alkylphthalimide, on alkaline hydrolysis gives the primary amine. Option D - Aryl halides do not undergo nucleophilic substitution with potassium phthalimide to form the aromatic primary amine.

Cyanobenzene can be easily prepared from ____.

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Cyanobenzene can be easily prepared from diazonium salt. The cyano group cannot be introduced by nucleophilic substitution of chlorine in chlorobenzene, but cyanobenzene can be easily obtained from diazonium salt.

The amides, on reduction with LiAlH4, give ____.

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The amides, on reduction with LiAlH4,give primary amines.

In aqueous phase, the substituted ammonium cations get stabilised by ____, ____ and ____of the alkyl groups.

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In aqueous phase, the substituted ammonium cations gets stabilised by +I effect, solvation and steric hindrance of the alkyl groups. Steric attraction, Steric repulsion, steric shielding and steric hindrance are the various types of steric effects.

Pick out the true statement about the basicity of aniline.

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The correct statement is, 'The unshared electron pair on the nitrogen atom is in conjugation with the benzene ring.' Option A - The pKb value of aniline is high. Option B - In aniline the -NH2 group is directly attached to the benzene ring. Option D - The unshared electron pair on the nitrogen atom is less available for protonation.

The IUPAC name of C2H5NH2 is ____.

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The correct IUPAC name for the structure C2H5NH2 is ethyl amine.

Aniline reacts with sodium nitrite and HCl to form ____ at 273-278 K.

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Aniline reacts with sodium nitrite and HCl to form benzenediazonium chloride at 273-278 K. The conversion of primary aromatic amines into diazonium salts is known as diazotisation. Due to its instability, the diazonium salt is generally not stored and is used immediately after its preparation.

Class 12th Chemistry - 13 Amines MCQs
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Class 12th Chemistry - 13 Amines MCQs