Is no2 compound a meta directing group????how to convert nitrobenzene to m-bromonitrobenzene???how to convert benzoic acid to phenol??Is it possible as they are aromatic compounds????

NO₂ is a meta-directiong group .

 

Nitrobenzene +Br₂ /CCl₄→  m-bromonitrobenzene

 

Phenol + Zn dust → Benzene 

 Benzene + CH₃Cl /AlCl₃ (anhyd.) → Toluene

Toluene + KMnO₄ → Benzoic Acid

from benzoic acid to phenol????

is no2 ortho and para directing group??........................................................................................................

Sorry, the correct pathway is : 

C₆H₅ - COOH + NaOH+CaO (High T& P) → C₆H₆ (Decarboxylation using sodalime)

C₆H₆ + Cl₂ + FeCl₃ → C₆H₅ - Cl  (Electrophilic Aromatic Substitution)

 C₆H₅ - Cl + NaOH + H⁺ (High T& P) →  C₆H₅ - OH ( Nucleophilic Aromatic Substitution)

 

NO₂ is definately a meta directing group. If you draw the resonating structures , positive charge comes at ortho and para positions , thus these places do not favour attack of electrophile as electrophiles are electron loving species .Thus electrophile attacks at meta position.

 

can u name some electrophiles?????????????????...........................................................................................

Electrophiles are electrom deficient molecules . They may be neutral such as BF₃  ,AlCl₃ , FeCl₃ ,PCl₅ ...etc or they may be positively charged H⁺,Cl⁺,Br⁺,NO₂⁺ …..etc. Positively charged electrophiles are generally used in Electrophilic Aromatic Substitution .For example  Cl₂ with AlCl₃ forms Cl⁺ electrophile and AlCl₄^- ,similarly CH₃Cl with AlCl₃ forms an electrophile CH₃⁺ . 

explain the basicity of amines in aqueous solutions????????????????????????????????????????????..........................................

You could have posted this as a new question on the forum. Nevertheless,

Basic strength in aq medium : (C₂H₅)₂NH > (C₂H₅)₃​N > (C₂H₅)​NH₂ >NH₃

                                            (CH₃)₂ NH >  (CH₃) NH₂ > (CH₃)₃N  >NH₃  

The above trend is generally observed because of the combined effect of  stability of their conjugate acid (due to H- bonding) and the Inductive effect of the alkyl group(s) . Greater the size of conj. acid less will be the solvation  and hence less stable will be the conj acid . Greater the stability of conj. acid greater is the basic strength. Due to steric hinderance of alkyl groups in H-bonding the stability order changes. You will have to memorize the above two orders as they are very important.( For more clarity NCERT part 2 Pg 390-391 ). By the way you haven’t approved any of my answers.

Regards