Which of the following compounds will react with sodium hydroxide solution in water?

1.  C6H5OH                       

2.   C6H5CH2OH

3.  CH33COH               

4.  C2H5OH

Hint: Stability of conjugate base directly proportional to acidity of compound

Phenol is more acidic in nature because by the loss of one proton, it gives phenoxide ion. This phenoxide ion is resonance stabilised. As phenoxide ion is a stable intermediate so, the tendency to give proton is more in phenol than the others .Phenols being more acidic than alcohols, dissolves in NaOH.

Therefore, option (a) is the correct.