JEE Main - Diazonium salts and their synthetic importance Online Test (MCQ Quiz)

1. Which of the following is the general formula for diazonium salts?

A) R-N≡N⁺ X⁻ B) R-NH₂⁺ X⁻ C) R-N=N-R D) R-N₂-R

2. Diazonium salts are typically prepared from primary aromatic amines by treatment with:

A) Dilute HCl and NaNO₂ B) Concentrated H₂SO₄ and KNO₃ C) Dilute HBr and NaNO₂ D) Concentrated HCl and KNO₃

3. The reaction of a primary aromatic amine with nitrous acid in the presence of a mineral acid at low temperature (0-5 °C) yields:

A) A diazonium salt B) A nitro compound C) An azo compound D) A nitrile

4. Why is the preparation of diazonium salts carried out at low temperatures (0-5 °C)?

A) To prevent decomposition of the diazonium salt B) To increase the solubility of the amine C) To facilitate the reaction with nitrous acid D) To prevent the formation of azo compounds

5. Which of the following is a characteristic property of diazonium salts in aqueous solution?

A) They are generally unstable and decompose readily B) They are highly stable and can be stored for long periods C) They are highly reactive and undergo nucleophilic substitution readily D) They are insoluble in water

6. The Sandmeyer reaction involves the conversion of a diazonium salt to:

A) A halobenzene using CuX (X = Cl, Br) B) A phenol using H₂O C) A nitrobenzene using NaNO₂ D) An aniline using H₂

7. In the Sandmeyer reaction, what is the role of copper(I) halide (CuX)?

A) Catalyst for the replacement of the diazonium group by halide B) Oxidizing agent C) Reducing agent D) Solvent

8. Which product is formed when benzenediazonium chloride reacts with CuCl/HCl?

A) Chlorobenzene B) Benzene C) Aniline D) Phenol

9. Which product is formed when benzenediazonium chloride reacts with CuBr/HBr?

A) Bromobenzene B) Chlorobenzene C) Aniline D) Benzene

10. The Gattermann reaction is similar to the Sandmeyer reaction but uses:

A) Copper powder and the corresponding acid (e.g., Cu/HCl) B) Copper(I) cyanide C) Water D) Potassium iodide

11. When benzenediazonium chloride is heated with water, the primary product formed is:

A) Phenol B) Aniline C) Benzene D) Chlorobenzene

12. The reaction of benzenediazonium chloride with potassium iodide (KI) yields:

A) Iodobenzene B) Benzene C) Aniline D) Phenol

13. The replacement of the diazonium group by a cyano group (-CN) can be achieved using:

A) CuCN/KCN B) CuCl/HCl C) CuBr/HBr D) KI

14. When benzenediazonium chloride reacts with CuCN/KCN, the product is:

A) Benzonitrile B) Aniline C) Benzene D) Chlorobenzene

15. The conversion of a diazonium salt to an aryl fluoride is known as the:

A) Schiemann reaction B) Sandmeyer reaction C) Gattermann reaction D) Balz-Schiemann reaction

16. In the Schiemann reaction, the diazonium salt is first treated with HBF₄ to form a diazonium tetrafluoroborate salt, which is then heated. This leads to the formation of:

A) Aryl fluoride B) Aryl chloride C) Aryl bromide D) Aryl iodide

17. Which of the following is used in the Schiemann reaction to introduce fluorine into the aromatic ring?

A) HBF₄ B) HCl C) HBr D) KI

18. The azo coupling reaction is characteristic of:

A) Diazonium salts B) Primary amines C) Secondary amines D) Alcohols

19. Azo coupling reactions typically occur between a diazonium salt and:

A) An activated aromatic compound (like phenol or aniline) B) An alkyl halide C) An alkane D) A carboxylic acid

20. Azo coupling reactions are usually carried out in a medium that is:

A) Weakly acidic or weakly alkaline B) Strongly acidic C) Strongly alkaline D) Neutral

21. The product of an azo coupling reaction contains the characteristic functional group:

A) -N=N- B) -NH₂ C) -OH D) -CN

22. Azo compounds are known for their use as:

A) Dyes B) Explosives C) Solvents D) Acids

23. When benzenediazonium chloride couples with phenol in alkaline medium, the product formed is:

A) p-Hydroxyazobenzene B) o-Hydroxyazobenzene C) Benzene D) Aniline

24. When benzenediazonium chloride couples with aniline in a weakly acidic medium, the product formed is:

A) p-Aminoazobenzene B) o-Aminoazobenzene C) Benzene D) Aniline

25. The reduction of diazonium salts with hypophosphorous acid (H₃PO₂) leads to the formation of:

A) Aromatic hydrocarbons B) Phenols C) Anilines D) Halobenzenes

26. The reaction of benzenediazonium chloride with H₃PO₂ yields:

A) Benzene B) Aniline C) Phenol D) Chlorobenzene

27. The replacement of the diazonium group by a hydrogen atom can be achieved using:

A) Hypophosphorous acid (H₃PO₂) B) Water C) Potassium iodide D) Copper(I) cyanide

28. The reaction of diazonium salts with ethanol can lead to:

A) Aromatic hydrocarbons and nitrogen gas B) Phenols C) Azo compounds D) Halobenzenes

29. When benzenediazonium chloride is treated with ethanol, the major products are:

A) Benzene and nitrogen gas B) Phenol and nitrogen gas C) Aniline and nitrogen gas D) Chlorobenzene and nitrogen gas

30. Which of the following is NOT a synthetic application of diazonium salts?

A) Preparation of alkenes B) Preparation of halobenzenes C) Preparation of phenols D) Preparation of azo dyes

31. Diazonium salts are important intermediates in the synthesis of:

A) A wide range of substituted aromatic compounds B) Aliphatic compounds only C) Inorganic compounds D) Simple hydrocarbons

32. The decomposition of diazonium salts in solution is an example of:

A) Nucleophilic substitution B) Electrophilic substitution C) Free radical substitution D) Addition reaction

33. What is the oxidation state of nitrogen in the diazonium group (-N₂⁺)?

A) +1 B) -1 C) 0 D) +3

34. The synthesis of 4-bromobenzoic acid from 4-aminobenzoic acid involves:

A) Diazotization followed by Sandmeyer reaction B) Direct bromination C) Reduction of nitro group D) Friedel-Crafts acylation

35. Which reagent is used to convert aniline to benzenediazonium chloride?

A) NaNO₂ + HCl (0-5 °C) B) KMnO₄ C) CrO₃ D) H₂SO₄ + KNO₃

36. The reason for the instability of diazonium salts is:

A) The strong tendency of the N₂ molecule to leave as a stable gas B) The presence of the highly reactive diazonium group C) Their high solubility in water D) Their susceptibility to oxidation

37. The coupling of a diazonium salt with a compound containing an active methylene group is possible under specific conditions. This is an example of:

A) Azo coupling B) Sandmeyer reaction C) Schiemann reaction D) Nucleophilic addition

38. Which of the following diazonium salt reactions is used to introduce an iodine atom into an aromatic ring?

A) Reaction with KI B) Sandmeyer reaction with CuCl C) Schiemann reaction D) Reduction with H₃PO₂

39. In the azo coupling reaction, the diazonium ion acts as an:

A) Electrophile B) Nucleophile C) Radical D) Oxidizing agent

40. The conversion of a diazonium salt to an aryl boronic acid can be achieved using:

A) Boric acid and a base B) Copper(I) cyanide C) Potassium iodide D) Hypophosphorous acid

41. Which reaction is most suitable for synthesizing fluorobenzene from aniline?

A) Balz-Schiemann reaction B) Sandmeyer reaction C) Gattermann reaction D) Azo coupling

42. The Sandmeyer reaction is a method for the replacement of the diazonium group by:

A) Halogens or cyano group B) Hydrogen or hydroxyl group C) Alkyl groups D) Amino group

43. What is the primary reason for the synthetic utility of diazonium salts?

A) The diazonium group can be easily replaced by a variety of nucleophiles B) They are extremely stable compounds C) They readily undergo electrophilic substitution D) They are highly colored and used as indicators

44. The reaction of benzenediazonium chloride with sodium borohydride (NaBH₄) can lead to:

A) Benzene B) Aniline C) Phenol D) Chlorobenzene

45. Which of the following is a characteristic property of diazonium salts that enables their use in coupling reactions?

A) Electrophilic nature of the diazonium ion B) Nucleophilic nature of the diazonium ion C) Strong oxidizing ability D) Strong reducing ability

46. The synthesis of substituted benzoic acids from substituted anilines often involves diazotization followed by:

A) Reaction with CuCN/KCN and subsequent hydrolysis B) Direct oxidation C) Reduction D) Halogenation

47. Which of the following diazonium salt reactions results in the formation of nitrogen gas as a byproduct?

A) Sandmeyer reaction B) Azo coupling C) Diazotization D) All of the above

48. The Balz-Schiemann reaction is specifically used for the synthesis of:

A) Aryl fluorides B) Aryl chlorides C) Aryl bromides D) Aryl iodides

49. The reaction of a diazonium salt with sodium nitrite in the presence of copper powder can introduce a nitro group into the aromatic ring. This is a variation of:

A) Gattermann reaction B) Sandmeyer reaction C) Schiemann reaction D) Azo coupling

Diazonium salts and their synthetic importance - Online Test

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