Amines Mock Test – Class 12 Chemistry

1. An arenediazonium salt reacts as a weak electrophile during azo coupling and therefore couples most readily with:

2. During protonation of a neutral amine, the donor–acceptor roles are described accurately by:

3. Examine the effects listed below.

The valid row is:

4. A storage plan for a diazonium salt is described below.
A student prepares a cold solution of benzenediazonium chloride and divides it into two portions. Portion P is kept in an ice bath. Portion Q is evaporated toward dryness and then warmed. The student plans to store both portions for later use.
Which safety assessment is most appropriate?

5. A neutral amine is converted into its protonated ammonium ion. Its immediate nucleophilicity at nitrogen decreases mainly because:

6. A mixture contains ethylamine and triethylamine. Treatment with excess benzoyl chloride under alkaline conditions gives of -ethylbenzamide, molar mass . After removal of the amide, the remaining base requires of hydrochloric acid. The original masses of ethylamine and triethylamine are:

7. The valid amide-reduction pair is:

8. The accurately named reagent–reaction pair is:

9. A graph plots boiling point on the vertical axis and carbon-atom count on the horizontal axis for a homologous series of straight-chain primary amines. The most reasonable overall shape is:

10. A sample of aniline is converted into sulphanilic acid. The chemical conversion is , and the product is isolated in yield. Calculate the isolated product mass and the mass of concentrated sulphuric acid theoretically consumed the converted material. Use , , and .

11. Assertion: The name -dimethylpropan-1-amine contains two -locants.
Reason: Each methyl group is attached directly to nitrogen rather than to a numbered carbon of the propane chain.

12. A sample of aniline undergoes the following sequence: is converted into acetanilide, of that material gives the desired -bromoacetanilide, and hydrolysis produces -bromoaniline in yield. Calculate the mass of -bromoaniline obtained and the amount of bromine consumed in the desired bromination step. Use , , and .

13. Acid treatment of an unreacted tertiary amine is represented by:

14. Assertion: Acetanilide is less readily protonated at nitrogen than aniline in a strongly acidic nitrating mixture.
Reason: The nitrogen lone pair of acetanilide is delocalised into the adjacent carbonyl group.

15. An unknown compound has molecular formula . It gives a positive carbylamine test and can be prepared by reduction of a nitrile obtained from -bromopropane and alcoholic . The unknown is:

16. Examine the nitrous-acid reactions below.

The valid rows are:

17. Assertion: Acidification of the alkaline solution obtained from a primary amine in the Hinsberg test produces a precipitate.
Reason: Acid converts the soluble sulphonamide salt back into the neutral, less water-soluble sulphonamide.

18. An aqueous extract contains of ethylammonium chloride and of excess hydrochloric acid. It is treated with of sodium hydroxide. Given and , the final is approximately:

19. A mixture containing of ethylamine is treated with of ethanoyl chloride and of benzoyl chloride in the presence of excess sodium hydroxide. Both acyl chlorides react completely and selectively form the corresponding amides. Using molar masses for -ethylethanamide and for -ethylbenzamide, the total amide mass and the minimum sodium hydroxide mass consumed are:

20. An alkylation product contains dimethylamine, trimethylamine, and of tetramethylammonium iodide. The total amount of nitrogen-containing species is , and the total number of moles of methyl groups attached to nitrogen is . The amounts of dimethylamine and trimethylamine, and the hydrochloric acid required to protonate all neutral amines, are:

21. When aniline is added to bromine water at room temperature, the characteristic observation is:

22. In the Brønsted–Lowry description, an amine behaves as a base when it:

23. From the Lewis acid–base viewpoint, a neutral amine is classified as a Lewis base because it:

24. A sample of aniline is treated with bromine water. The chemical conversion to -tribromoaniline is , and the product is isolated in yield. Using and , the isolated product mass is:

25. Examine the Sandmeyer reactions below.

The valid rows are:

26. A cold aqueous solution contains (14.05 mathrm{g}) of benzenediazonium chloride. On warming with excess water, (80.0%) of the diazonium salt is converted into phenol, and the phenol is isolated in (75.0%) yield. Calculate the isolated phenol mass and the volume of nitrogen formed at STP. Use (M(mathrm{C_6H_5N_2Cl})=140.5 mathrm{g,mol^{-1}}), (M(mathrm{phenol})=94.0 mathrm{g,mol^{-1}}), and (22.4 mathrm{L,mol^{-1}}) at STP.

27. Examine the predictions below.

The valid row is:

28. Acylation can distinguish a secondary amine from a tertiary amine because:

29. Which decreasing basicity order is most reasonable?

30. Relative electrophilic-substitution rate is plotted against the fraction of aniline present as anilinium ion. Which overall trend is most reasonable?

31. A hypothetical graph compares two predicted aqueous-basicity trends as the number of alkyl groups on nitrogen increases. Curve P rises continuously because it considers only the positive inductive effect. Curve Q rises initially but then levels off or falls for highly substituted amines. Curve Q differs from P mainly because Q includes:

32. Compare the two nitration procedures described below.
Two students nitrate equal amounts of aniline. Student P performs direct nitration in concentrated acids. Student Q first converts aniline into acetanilide, carries out nitration under controlled conditions, and finally hydrolyses the nitrated product. Student P obtains a mixture containing a substantial meta isomer, whereas Student Q obtains mainly one isomer.
The major final product obtained by Student Q is:

33. Two weak amines P and Q have equal initial concentrations. If

the approximate ratio

is:

34. The standard aqueous basicity order for methyl-substituted amines is:

35. An organic layer initially contains of aniline. It is extracted with enough hydrochloric acid to protonate only of aniline. The aqueous extract is then treated with of sodium hydroxide. If of the liberated aniline is finally isolated, which record is correct? Use .

36. Assertion: Direct nitration of aniline does not give only ortho- and para-nitroaniline.
Reason: The strongly acidic nitrating medium converts a significant fraction of aniline into anilinium ion, which is meta directing.

37. A molecule of water approaches trimethylamine. The most favourable hydrogen-bond arrangement is:

38. In the Hoffmann rearrangement of a primary amide, the intermediate formed by bromination at nitrogen is:

39. Ordinary Friedel–Crafts alkylation or acylation of aniline generally fails under standard -catalysed conditions because:

40. The structure represents:

41. The relation between and is completed by

42. Base P has , and base Q has . The ratio is:

43. In a substitution reaction where access to the electrophilic carbon is strongly restricted by steric effects, methylamine may react faster than tert-butylamine because:

44. The sulphonamide formed from a primary amine dissolves in excess aqueous alkali because:

45. A reaction centre contains an amine nitrogen with an available lone pair and a positively polarised carbon atom. Their most likely roles are:

46. Assertion: A quaternary ammonium ion containing four different groups may retain a stable configuration at nitrogen.
Reason: Its nitrogen has four sigma bonds and lacks the lone pair required for ordinary pyramidal inversion.

47. In an arenediazonium ion, the charge on the group is ______.

48. Three isomeric amines P, Q, and R have the formula . P has two bonds, Q has one bond, and R has none. Their most likely decreasing boiling-point order is:

49. Use the following passage.
An unknown amine reacts with benzenesulphonyl chloride in aqueous alkali and produces a neutral solid. The solid remains unchanged and insoluble when more alkali is added. Acidification of the mixture produces no new precipitate because the solid was never converted into a soluble salt.
The unknown amine is most likely:

50. Which structural feature identifies a nitrogen atom as an amide nitrogen rather than an ordinary amine nitrogen?