CBSE Class 12 Chemistry Halo alkanes and Haloarene (1). CBSE issues sample papers every year for students for class 12 board exams. Students should solve the CBSE issued sample papers to understand the pattern of the question paper which will come in class 12 board exams this year. The sample papers have been provided with marking scheme. It’s always recommended to practice as many CBSE sample papers as possible before the board examinations. Sample papers should be always practiced in examination condition at home or school and the student should show the answers to teachers for checking or compare with the answers provided. Students can download the sample papers in pdf format free and score better marks in examinations. Refer to other links too for latest sample papers.
1 MARK QUESTIONS
1. What happens when tert-butyl alcohol is treated with Cu / at 573 K.?
2. Arrange the following halides in order of increasing SN² reactivity :
CH3 — Cl, CH3 — Br, CH3CH2Cl, (CH3)2 CHCl
3. Alkyl halides, though polar, are immiscible with water. Why?
4. Grignard reagents should be prepared under anhydrous conditions. Why?
5. Which of the following two compounds would react faster by SN² pathway: 1-bromobutane (OR) 2-bromobutane.
6. Allyl Chloride is more reactive than n-propyl Chloride towards nucleophilic substitution reactions. Explain.
7. Explain why is Chlorobenzene difficult to hydrolyse than ethyl chloride ?
8. R—Cl is hydrolysed to R—OH slowly but the reaction is rapid if a catalytic amount of KI is added to the reaction mixture.Why?
9. Why haloalkanes are more reactive than haloarenes.
10. Why do haloalkenes undergo nucleophillic substitution whereas haloarenes under go electophillic substitution?
11. Aryl halides cannot be prepared by the action of sodium halide in the presence H2SO4 .Why?
12. Why is Sulphuric acid not used during the reaction of alcohols with KI ?
13. p- dichlorobenzene has highest m.p. than those of ortho and m-isomers.?
14. Although chlorine is an electron- withdrawing group, yet it is ortho and para directing in electrophillic aromatic substitution reactions.Why?
15. Explain why vinyl chloride is unreactive in nucleophillic substitution reaction?
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