CBSE Class 12 Chemistry Worksheet - Revision (3). 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.
Q1. How will you convert the following:
a) Benzene to diphenyl
b) Isopropyl chloride to n-propylbromide
c) Acetylene to propyne
d) Methyl bromide to acetic acid
e) Chlorobenzene to p-nitrophenol
Q2. What happens when:
a) Ethylbromide is reacted with AgCN.
b) Chloroform reacts with aniline in the presence of alcoholic KOH.
c) Benzene diazoniumchloride reacts with HCl in the presence of Cu powder.
Q3. Distinguish between:
a) Chlorobenzene and benzyl chloride
b) Ethyl alcohol and propyl alcohol
c) Bromoethane and Chloroethane
Q4. With alcoholic potash compound A (C3H7Br) gives B(C3H6). On oxidation B gives acetic acid, CO2 and water. With HBr, it gives D, an isomer of A. Identify compounds A to D.
Q5. Explain why
a) Chlorine although electron withdrawing, yet is o- and p- directing in electrophilic aromatic substitution reactions.
b) 2-Bromobutane is chiral whereas Bromobutane is achiral.
Q6. Give the IUPAC names of the following compounds:
b) (CH3)2C = CHCH2Br
Q7. Write all the possible structures for the molecular formula C5H11Br. Give their IUPAC names and classify the isomers as 1o, 2o or 3o. Which of these are optically active?
Q8. Predict the order of reactivity of four isomeric iodobutane in SN1 and SN2 reactions.
Q9. Haloalkanes undergo nucleophilic substitution reactions while haloarenes undergoes electrophilic substitution reactions. Explain.
Q10. The treatment of alkyl chlorides with aqueous KOH leads to the formation of alcohols but in the presence of alcoholic KOH, alkenes are major products.Why?
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