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Class 12 Chemistry  MCQ Questions of Amines with Answers?

Answer 1

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Practice MCQ Question for Class 12 Chemistry chapter-wise

1. Nitrogen atom of amino group is ………. hybridised.

(a) sp
(b) sp²
(c) sp³
(d) sp³d

2. C₃H₈N cannot represent

(a) 1° ammine
(b) 2° ammine
(c) 3° ammine
(d) quartemary ammonium salt

3. The most convenient method to prepare primary (i Amine) amine containing one carbon atom less is

(a) Gabriel phthalmidie synthesis
(b) Reductive amination of aldehydes
(c) Hofmann bromamide reaction
(d) Reduction of isonitriles

4. When excess of ethyl iodide is treated with ammonia, the product is

(a) ethylamine
(b) diethylamine
(c) triethylamine
(d) tetrathylammonium iodide

5. Amides may be converted into amines by a reaction named after

(a) Hofmann Bromide
(b) Claisen
(c) Perkin
(d) Kekule

6. Benzoic acid is treated with SOCl₂ and the product (X) formed is reacted with ammonia to give (Y). (Y) on reaction with Br2 and KOH gives (Z). (Z) in the reaction is

(a) aniline
(b) chlorobenzene
(c) benzamide
(d) benzoyl chloride

7. Amine that cannot be prepared by Gabricl- Phthalmidie synthesis is

(a) aniline
(b) benzyl amine
(c) methyl amine
(d) iso-butylamine

8. Tertiary amines have lowest boiling points amongst isomeric amines because

(a) they have highest molecular mass
(b) they do not form hydrogen bonds
(c) they are more polar in nature
(d) they are most basic in nature

9. Primary and secondary amines are distinguished by

(a) Br₂/ROH
(b) HClO
(c) HNO₂
(d) NH₃

10. Which of the following is used as Hinsberg’s reagent?

(a) C₆H₅SO₂Cl
(b) C₆H₅SO₃H
(c) C₆H₅NHCH₃
(d) C₆H₅COCH

11. Anilinium hydrogen sulphate on heating with sulphuric acid at 453-473 K produces

(a) sulphanilic acid
(b) benzenesulphonic acid
(c) aniline
(d) anthranilic acid

12. When aniline is heated with conc. H₂SO₄ at 455−475K, it forms

(a) aniline hydrogensulphate
(b) sulphanilic acid
(c) amino benzene sulphonic acid
(d) benzenesulphonic acid

13. The amines are basic in nature, hence they form salts with hydrochloric acid. Which of the following will be insoluble in dil. HCl?

(a) C₆H₅NH₃
(b) (C₆H₅)₃N
(c) C₂H₅NH₂
(d) CH₃NHCH₃

14. Amines have

(a) Garlic odour
(b) Fishy odour
(c) Jasmine odou
(d) Bitter almonds odour

15. The best reagent for converting 2 – phenylpropanamide into 2-phenylpropanamine is ..........

(a) excess H₂
(b) Br₂ in aqueous NaOH
(c) iodine in the presence of red phosphorus
(d) LiAlH₄ in ether

16. Reaction of aniline with benzaldehyde is

(a) substitution
(b) addition
(c) condensation
(d) polymerization

17. Aniline is used

(a) in crimping of wool
(b) in dyeing industry
(c) in making of glue
(d) in fast drying vanish

18. When a primary amine reacts with chloroform in ethanolic KOH, then the product is

(a) isocyanide
(b) aldehyde
(c) cyanide
(d) alcohol

19. An organic compound A on reduction gives compound B which on reaction with chloroform and potassium hydroxide forms C. The compound C on catalytic reduction gives N-methylaniline. The compound A is

(a) Nitrobenzene
(b) Nitromethane
(c) Methylamine
(d) Aniline

20. Acetamide and ethyl amine can be distinguished by reacting with             

(a) aq. HCl and heat
(b) aq. NaOH and heat
(c) acidified KMnO₄
(d) bromine water

21. Primary nitroalkanes on hydrolysis give:

(a) RCOOH + NH₂OH
(b) RCOOH
(c) NH₂OH
(d) RCOR

22. RMgX on reacting with cyanogen chloride gives:

(a) R-NC
(b) R-Cl
(c) R-CN
(d) None of the above

23. The compound obtained by heating a mixture of primary amine and chloroform with ethanolic potassium hydroxide (KOH) is

(a) An alkyl isocyanide
(b) An alkyl halide
(c) An amide
(d) An amide and nitro compound

24. Alkyl halide (RX) on treatment with KCN followed by reduction leads to the formation of:

(a) RNH₂
(b) RCH₂NH₂
(c) RH + NH₃
(d) RCH₃ + N₂

25. Gas evolved during the reacton of sodium metal on ethyl-amine is:

(a) N₂
(b) C₂H₂
(c) H₂
(d) CO₂

Answer 2

 1. Answer :  sp³ 

Explanation: The nitrogen atom in most amines is sp³ hybridized. Three of the sp³ hybrid orbitals form sigma bonds with the fourth orbital carrying the lone pair electrons. Single-bonded nitrogen is trigonal pyramidal in shape, with the non-bonding lone electron pair pointing to the unoccupied corner of a tetrahedron.

2. Answer : (d) quartemary ammonium salt

Explanation: Here the nitrogen atom is surrounded by two carbon atoms. So we cannot represent C₃H₈N it as quaternary salt.

3. Answer : (c) Hofmann bromamide reaction

Explanation: Hofmann bromamide reaction is the best method to reduce one carbon atom in the amine from amide.

4. Answer : (d) tetrathylammonium iodide

Explanation: In the ammonolysis reaction of an alkyl halide with ammonia, ammonia acts as nucleophile. The product formed would be quaternary salt of ammonia. the reaction as, 

NH₃ + C₂H₅I (excess) → (C₂H₅)₄N⁺ 

From the above reaction, we can see that when ethyl iodide in excess is made to react with ammonia, the product formed would be tetraethylammonium iodide.

5. Answer : (a) Hofmann Bromide

Explanation: Amides can be converted into amines by Hofmann's bromamide reaction. This reaction is named after Hofmann.

6. Answer : (a) aniline

Explanation:

 

7. Answer : (a) aniline

Explanation: Only aliphatic primary amines can be prepared by Gabriel synthesis. Aniline cannot be prepared by this method because aryl halides ( C₆H₅Cl or C₆H₅Br ) do not undergo nucleophilic substitution with potassium phthalimide under ordinary conditions to give N-phenyl phthalimide (ie, cleavage of CX bond in haloarenes is quite difficult)

8. Answer : (b) they do not form hydrogen bonds

Explanation: Primary and secondary amines can form hydrogen bonds whereas tertiary amines fail to do so. So, their boiling points are lowest.

9. Answer : (c) HNO₂

Explanation: The general formula of primary amine is R−NH2 and the general formula of secondary amine is R₂−NH. So, these can be distinguished by nitrous acid whose formula is HNO₂.

10. Answer : (a) C₆H₅SO₂Cl

Explanation: Benzenesulphonyl chloride (C₆H₅SO₂CI) is known as Hinsberg reagent It reacts with primary and secondary amines to form sulphonamides.

11. Answer : (a) sulphanilic acid

Explanation: The Sulphanilic acid the rearranges to form Zwitter ion. So, Anilinium hydrogen sulphate on heating with sulphuric acid at 453 - 473K produces Sulphanilic acid.

12. Answer : (b) sulphanilic acid

Explanation:

 

13. Answer : (b) (C₆H₅)₃N

Explanation: There is no free hydrogen in tertiary amines hence they do not form salts and are not soluble in acids.

14. Answer : (b) Fishy odour

Explanation: Amines are basic compounds with strong odors. The odor of amines is often described as "fishy" since the odor of raw fish comes from the amines contained. Sometimes even "foul smelling" is an understatement, and two of the amines produced in decaying flesh have suggestive names (cadaverine and putresine).

15. Answer : (d) LiAlH₄ in ether

Explanation:

 

16. Answer : (c) condensation

Explanation: The reaction of benzaldehyde with aniline produces benzalaniline which is a condensation reaction.

17. Answer : (b) in dyeing industry

Explanation: Illustrative of the drugs prepared from aniline is paracetamol (acetaminophen, Tylenol). The principal use of aniline in the dye industry is as a precursor to indigo, the blue of blue jeans.

18. Answer : (a) isocyanide

Explanation: Primary amines (both aromatic and aliphatic) when heated with chloroform and alcoholic KOH, isocyanides or carbylamines are formed and the reaction is called a carbylamine reaction. The newly formed product has an offensive smell. This reaction is answered only by primary amines.

19. Answer : (a) Nitrobenzene

Explanation :

 

20. Answer : (b) aq. NaOH and heat

Explanation: Acetamide in the presence of NaOH and heat changes to acetic acid while ethylamine does not undergo any reaction.

21. Answer : (a) RCOOH + NH₂OH

Explanation : Primary nitroalkanes undergo hydrolysis when heated with 85 per cent sulphuric acid to form hydroxylamine sulphate and the corresponding carboxylic acid. Addition of the sodium salt of the aci form of a primary or secondary nitroalkane to excess dilute sulphuric acid gives an aldehyde or ketone respectively.

22. Answer : (c) R-CN

Explanation : Alkyl cyanides are produced when Grignard reagents react with cyanogen and cyanogen chloride . When an alkyl magnesium chloride or bromide is treated with iodine, alkyl iodides are formed.

23. Answer : (a) An alkyl isocyanide

Explanation : The compound obtained by heating a mixture of a primary amine and chloroform with ethanolic potassium hydroxide (KOH) is an alkyl isocyanide. The reaction of a primary amine with chloroform in the presence of ethanolic potassium hydroxide is called a carbylamine reaction or Hoffman's isocyanide test.

24. Answer : (b) RCH₂NH₂

Explanation : Electron density on N is higher. Then, R attaches to N and will form RNC and AgX. That's why, when haloalkanes reacts with KCN it will form alkane nitrile or alkyl cyanide and when haloalkanes reacts with AgCN it gives isocyanide.

25. Answer : (c) H₂

Explanation: When ethylamine is heated with sodium metal, then hydrogen gas is evolved.

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