Question

Which one of the following compounds is most acidic?

• A.

  

• B.

  

• C.

  

• D.

  

Answer 1

The Correct Option is B

Phenols are much more acidic than alcohols due to the stabilisation of phenoxide ion be resonance.

ortho-nitrophenol is most acidic because in it $- NO _{2}$ electron attracting group is attached on ortho-position which helps in stabilizing of negative charge on the oxygen of phenoxide ion. Hence, due to this reason acidic character of phenol is increased, while on attachment of $- CH _{3}$ group (electron donating group) acidic strength of phenol is decreased in cresol due to destabilization of phenoxide ion.