Haloalkanes and Haloarenes
127 CBSE Class 12 Chemistry previous year questions (PYQs) from 4 papers, 2023 to 2026, with answers and worked solutions.
About this chapter
- Difficulty: 31 easy · 88 moderate · 8 hard.
- Most-asked subtopics: Chemical Reactions (93), Methods of Preparation of Haloalkanes (11), Physical Properties (7).
- Updated 13 September 2026.
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#1ModerateChemical Reactions
#2ModerateChemical Reactions
#3ModerateHas imageChemical Reactions
#4EasyChemical Reactions
#5ModerateHas imageMethods of Preparation of Haloalkanes
#6ModerateChemical Reactions
#7ModerateMethods of Preparation of Haloalkanes
#8ModerateChemical Reactions
#9ModerateChemical Reactions
#10ModerateChemical Reactions
#11EasyChemical Reactions
#12ModerateChemical Reactions
#13EasyClassification
#14ModerateChemical Reactions
#15ModerateChemical Reactions
#16ModerateHas imageChemical Reactions
#17ModerateHas imageChemical Reactions
#18ModeratePhysical Properties
#19EasyChemical Reactions
#20EasyMethods of Preparation of Haloalkanes
#21ModerateChemical Reactions
For questions number 13 to 16, two statements are given one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :#22ModerateChemical Reactions
#23ModerateChemical Reactions
#24ModerateChemical Reactions
#25ModerateChemical Reactions
#26ModerateChemical Reactions
#27ModerateHas imageChemical Reactions
#28ModerateMethods of Preparation of Haloalkanes
#29ModerateHas imageChemical Reactions
#30ModerateHas imageMethods of Preparation of Haloalkanes
#31ModerateChemical Reactions
#32EasyChemical Reactions
#33ModerateHas imageChemical Reactions
#34EasyHas imageClassification
#35ModerateChemical Reactions
#36ModerateChemical Reactions
#37EasyChemical Reactions
#38ModerateChemical Reactions
Nucleophilic Substitution reaction of haloalkane can be conducted according to both and mechanisms. is a two step reaction while is a single step reaction. For any haloalkane which mechanism is followed depends on factors such as structure of haloalkane, properties of leaving group, nucleophilic reagent and solvent. Influences of solvent polarity : In reaction, the polarity of the system increases from the reactant to the transition state, because a polar solvent has a greater effect on the transition state than the reactant, thereby reducing activation energy and accelerating the reaction. In reaction, the polarity of the system generally does not change from the reactant to the transition state and only charge dispersion occurs. At this time, polar solvent has a great stabilizing effect on Nu than the transition state, thereby increasing activation energy and slow down the reaction rate. For example, the decomposition rate of tertiary chlorobutane at 25 °C in water (dielectric constant 79) is 300000 times faster than in ethanol (dielectric constant 24). The reaction rate of 2-Bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. Hence the level of solvent polarity has influence on both and reaction, but with different results. Generally speaking weak polar solvent is favourable for reaction, while strong polar solvent is favourable for . Generally speaking the substitution reaction of tertiary haloalkane is based on mechanism in solvents with a strong polarity (for example ethanol containing water).#39EasyClassification
#40ModerateChemical Reactions
#41ModerateChemical Reactions
Given below are two statements labelled as Assertion (A) and Reason (R). Select the most appropriate answer from the options given below :#42ModerateChemical Reactions
#43ModeratePolyhalogen Compounds
#44ModerateClassification
#45EasyPhysical Properties
#46EasyPolyhalogen Compounds
#47EasyChemical Reactions
#48ModerateNature of C-X Bond
Given below are two statements labelled as Assertion (A) and Reason (R). Select the most appropriate answer from the options given below :#49ModerateHas imagePreparation of Haloarenes
#50ModerateChemical Reactions
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