Chemistry Class 12
Solutions to CBSE Sample Paper - Chemistry Class 12

Give reasons for any 3 of the following observations:

a. Aniline is acetylated before nitration reaction.

b. pKb of aniline is lower than the m-nitroaniline.

c. Primary amine on treatment with benzenesulphonyl chloride forms a product which is soluble in NaOH however secondary amine gives product which is insoluble in NaOH.

d. Aniline does not react with methyl chloride in the presence of anhydrous AlCl 3 catalyst.



a. Aniline is acetylated, before nitration reaction in order to avoid formation of tarry oxidation products and protecting the amino group, so that p -nitro derivative can be obtained as major product.

b.pKb of aniline is lower than the m-nitro aniline.The basic strength of aniline is more that m-nitroaniline . pkb value is inversely proportional to basic strength.

Presence of Electron withdrawing group decrease basic strength.

c. Due to the presence of acidic hydrogen in the N-alkylbenzenesulphonamide formed by the treatment of primary amines.

d. Aniline does not react with methylchloride in the presence of AlCl 3 catalyst ,because aniline is a base and AlCl 3 is Lewis acid which lead to formation of salt.

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.