Phenol,when it first reacts with conc.sulphuric acid and then with conc.nitric acid gives

a)o-nitro phenol b)p-itrophenol c)nitrobenzene

d)2,4,6-trinitrobenzene

please explain in detail.

Dear vikas

this is the method of formation of picric acid( 2,4,6-trinitrobenzene)

first when it reacts with cons sulphuric acid mixure of o-phinol sulphonic acid and p-phenol sulphonic acid forms 

and when this mix reacts with cons nitric acid  then picric acid form.

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