Haloalkanes and Haloarenes Mock Test – Class 12 Chemistry

1. Assertion: Reduction of a monohaloalkane normally preserves the number of carbon atoms in its organic skeleton.
Reason: The transformation replaces the halogen atom by hydrogen rather than coupling two carbon groups.

2. For haloalkanes having the same carbon skeleton, the broad density trend is most reasonably predicted as:

3. An allylic carbocation is more stable than a comparable ordinary primary carbocation mainly because:

4. Assertion: All apparatus used for preparing a Grignard reagent should be thoroughly dry.
Reason: Water protonates the carbon bonded to magnesium and converts the Grignard reagent into a hydrocarbon.

5. A practical notebook contains the following proposed diazonium conversions.

The row that requires correction is:

6. Read the situation below and answer the question.

Compound P is , while compound Q is . Both are heated with alcoholic . Compound Q forms an alkene readily, but P does not undergo ordinary beta-elimination.

Which explanation is correct?

7. Assertion: The carbon–halogen bond-breaking step is usually the slow step in an ideal reaction.
Reason: Formation of separated ions from a neutral haloalkane requires substantial energy.

8. Assess the following information about the reaction .

The appropriate evaluation is:

9. When chloromethane reacts with hydroxide ion by substitution, the organic product is:

10. Study the following descriptions of a halogen substituent on benzene.

The appropriate evaluation is:

11. Which equation represents reduction of a haloalkane to a hydrocarbon?

12. Match each molecular formula in Column I with its classification in Column II.

13. Which equation correctly represents the formation of a Grignard reagent from an alkyl halide?

14. A facility uses a volatile chlorinated solvent and also handles a persistent organohalogen pesticide. Which management plan best addresses both immediate and long-term risks?

15. Three chlorides are compared under substitution conditions:
P.
Q.
R.

The compound in which chlorine is attached to a benzylic carbon is:

16. Assess the following stages of chlorofluorocarbon-related ozone depletion.

The appropriate evaluation is:

17. When chlorobenzene is heated with aqueous sodium hydroxide at about under high pressure, the immediate organic product is:

18. Assess the following statements about common names of simple haloalkanes.
Statement I: The alkyl-group name is written before fluoride, chloride, bromide, or iodide.
Statement II: The common-name system always uses numbered locants to show the halogen position.
Statement III: Terms such as isopropyl and tert-butyl describe the structure of the alkyl group.

19. The claim “Choosing a polar aprotic solvent is sufficient to make every haloalkane react by ” is:

20. Assertion: favours formation of nitroalkanes from haloalkanes.
Reason: The relatively covalent silver nitrite reagent favours attack through nitrogen rather than through oxygen.

21. Study the following reagent–product records.

Which row is mismatched?

22. Why can a small amount of chlorine released from chlorofluorocarbons destroy a much larger amount of ozone?

23. Replacement of an aromatic diazonium group is strongly favoured because the leaving species formed is:

24. Inspect the following reaction-planning assignments.

The appropriate evaluation is:

25. Propene can be converted into butanenitrile by:

26. A student claims, “Because halogen is the leaving group, it must leave before the nucleophile approaches an activated haloarene.” The most accurate correction is:

27. In the fragment , the carbon directly bonded to and the next carbon along the chain are called, respectively:

28. Among the following compounds, the one having its halogen directly attached to an aromatic ring is:

29. The best condition for converting -bromopropane mainly into propan--amine while limiting further alkylation is:

30. Methyl bromide is treated separately with and . The principal products obtained with these reagents, respectively, are:

31. Assertion: Potassium iodide can convert benzenediazonium chloride into iodobenzene without the usual Sandmeyer copper(I) catalyst.
Reason: Loss of stable allows iodide ion to replace the diazonium group readily.

32. Analyse the following ideal stereochemical outcomes.

The appropriate evaluation is:

33. Which equation best represents a Swarts reaction using silver fluoride?

34. Beta-elimination rather than nucleophilic substitution is expected to dominate for:

35. Which reagent sequence converts ethanol into propanenitrile?

36. Nitration of chlorobenzene produces both ortho- and para-substituted products, with the para isomer often present in the larger amount. Which explanation accounts for this result?

37. Four halo compounds are tested under conditions chosen for their characteristic reactions.
P. with a strong nucleophile in a polar aprotic solvent
Q. in aqueous ethanol
R. with aqueous hydroxide
S. with mild aqueous hydroxide
Select the combined interpretation supported by these tests.

38. The common name “methylene chloride” refers to:

39. Inspect the reaction-stage information below.

The appropriate evaluation is:

40. Carbon tetrachloride was formerly used in some fire-extinguishing applications mainly because it:

41. In a reaction-coordinate diagram, the vertical and horizontal axes usually represent, respectively:

42. A graph of molecular dipole moment against the sequence , , , and should not automatically be expected to show a smooth electronegativity-based decrease because:

43. Arrange the following operations in sequence for preparing benzoic acid from bromobenzene.
P. React bromobenzene with magnesium in dry ether.
Q. Pass carbon dioxide into the organomagnesium reagent.
R. Form the magnesium salt of benzoic acid.
S. Carry out acidic hydrolysis.

44. The rise in boiling point from an alkyl chloride to the corresponding alkyl iodide is mainly associated with:

45. Which comparison between Sandmeyer and Gattermann reactions is correct?

46. DDT concentrations in an aquatic sample and in fish-eating bird tissue are and , respectively. On this common mass basis, the concentration in the bird tissue is greater by a factor of:

47. Check the following statements.
Statement I: The carbon–iodine bond is generally longer than the carbon–chlorine bond in comparable haloalkanes.
Statement II: A longer carbon–halogen bond is necessarily stronger than a shorter one.
Statement III: Carbon–halogen bond-length comparisons should preferably use similar carbon skeletons.

48. A reaction record describes the behaviour of -bromopropane under two conditions.

Case P: dilute aqueous hydroxide at lower temperature gives mainly propan--ol.
Case Q: concentrated alcoholic hydroxide with heating gives mainly propene.

The best interpretation is:

49. Between chloromethane, , and carbon tetrachloride, , the molecule having a non-zero dipole moment is:

50. Assertion: Old chloroform that has been exposed to air and light may be unsafe to use.
Reason: Chloroform can be oxidised by oxygen in the presence of light to form poisonous phosgene.